A is the first letter of the Latin and English alphabet. A may also refer to:

Science and technology

Quantities and units

* ''a'', a measure for the attraction between particles in the

Van der Waals equation The van der Waals equation is a mathematical formula that describes the behavior of real gases. It is an equation of state that relates the pressure, volume, Avogadro's law, number of molecules, and temperature in a fluid. The equation modifies ...

* ''A'' value, a measure of substituent effects on the stereochemistry of cyclohexane * absorbance (''A'') *

acceleration In mechanics, acceleration is the Rate (mathematics), rate of change of the velocity of an object with respect to time. Acceleration is one of several components of kinematics, the study of motion. Accelerations are Euclidean vector, vector ...

(''a'') * activity (chemistry) (''a'') *

adsorption Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a ...

(a) *

annum A year is a unit of time based on how long it takes the Earth to orbit the Sun. In scientific use, the tropical year (approximately 365 solar days, 5 hours, 48 minutes, 45 seconds) and the sidereal year (about 20 minutes longer) are more e ...

(a), for year * are (a), a unit of area (equal to 100 square metres; redirects to ''hectare'') *

atto- A metric prefix is a unit prefix that precedes a basic unit of measure to indicate a multiple or submultiple of the unit. All metric prefixes used today are decadic. Each prefix has a unique symbol that is prepended to any unit symbol. The pre ...

(a-), the SI prefix meaning 10⁻¹⁸ *

Ampere The ampere ( , ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to 1 c ...

(A), unit of electric current *

ångström The angstrom (; ) is a unit of length equal to m; that is, one ten- billionth of a metre, a hundred-millionth of a centimetre, 0.1 nanometre, or 100 picometres. The unit is named after the Swedish physicist Anders Jonas Ångström (1814� ...

(Å) a unit of length (equal to 1 metres) *

area Area is the measure of a region's size on a surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an open surface or the boundary of a three-di ...

(''A'') *

attenuation coefficient The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient val ...

(''a'') * Bohr radius (''a''₀) *

chemical affinity In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to com ...

(''A'') *

gain (electronics) In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port by adding energy converted from some power supply to the signal. It i ...

(''A'') *

Hall coefficient The Hall effect is the production of a potential difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was d ...

(''A''_H) * Hamaker constant (''A'') *

Helmholtz free energy In thermodynamics, the Helmholtz free energy (or Helmholtz energy) is a thermodynamic potential that measures the useful work obtainable from a closed thermodynamic system at a constant temperature ( isothermal). The change in the Helmholtz ene ...

(''A'') * Hyperfine coupling constant (''a'' or ''A'') *

magnetic vector potential In classical electromagnetism, magnetic vector potential (often denoted A) is the vector quantity defined so that its curl is equal to the magnetic field, B: \nabla \times \mathbf = \mathbf. Together with the electric potential ''φ'', the ma ...

(''A'') *

mass number The mass number (symbol ''A'', from the German word: ''Atomgewicht'', "atomic weight"), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is appro ...

of a nuclide (''A'') *

pre-exponential factor In chemical kinetics, the pre-exponential factor or A factor is the pre-exponential constant in the Arrhenius equation (equation shown below), an empirical relationship between temperature and rate coefficient. It is usually designated by A w ...

(''A'') * one of the

reciprocal lattice vector Reciprocal lattice is a concept associated with solids with translational symmetry which plays a major role in many areas such as X-ray and electron diffraction as well as the energies of electrons in a solid. It emerges from the Fourier tran ...

s (''a*'') *

relative atomic mass Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a gi ...

(''A''_r) *

Richardson's constant Thermionic emission is the liberation of charged particles from a hot electrode whose thermal energy gives some particles enough kinetic energy to escape the material's surface. The particles, sometimes called ''thermions'' in early literature, ...

(''A'') *

rotational constant In rotordynamics, the rigid rotor is a mechanical model of rotating systems. An arbitrary rigid rotor is a 3-dimensional rigid object, such as a top. To orient such an object in space requires three angles, known as Euler angles. A special r ...

(''A'') *

specific surface area Specific surface area (SSA) is a property of solids defined as the total surface area (SA) of a material per unit mass, (with units of m2/kg or m2/g). Alternatively, it may be defined as SA per solid or bulk volume (units of m2/m3 or m−1). I ...

(''a'') *

thermal diffusivity In thermodynamics, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It is a measure of the rate of heat transfer inside a material and has SI, SI units of m2/s. It is an intensive ...

(''a'') *

unit cell length In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessaril ...

(''a'')

Astronomy

* A whitish-blue class of stars in the Morgan–Keenan system; see

Stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...

* Part of the provisional designation of a comet (e.g., C/1760 A1), indicating a January 1 through 15 discovery * The

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

of an orbit

Biology

* A+ and A−, human

blood type A blood type (also known as a blood group) is based on the presence and absence of antibody, antibodies and Heredity, inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycop ...

s *

Vitamin A Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most not ...

, also called retinol, an essential human nutrient *

Haplogroup A (mtDNA) In human mitochondrial genetics, Haplogroup A is a human mitochondrial DNA (mtDNA) haplogroup. Origin Haplogroup A is believed to have arisen in Asia some 30,000–50,000 years BC. Its ancestral haplogroup was Haplogroup N. However, the ext ...

, a human mitochondrial DNA (mtDNA) haplogroup * Haplogroup A (Y-DNA), a Y-chromosomal DNA (Y-DNA) haplogroup *

Adenine Adenine (, ) (nucleoside#List of nucleosides and corresponding nucleobases, symbol A or Ade) is a purine nucleotide base that is found in DNA, RNA, and Adenosine triphosphate, ATP. Usually a white crystalline subtance. The shape of adenine is ...

, a nucleic acid *

Adenosine Adenosine (symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9- glycosidic bond. Adenosine is one of the four nucleoside build ...

, a nucleoside * A (or Ala), abbreviation for amino acid

alanine Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group sid ...

* ATC code A, Alimentary tract and metabolism, a section of the Anatomical Therapeutic Chemical Classification System

Computing

Programming languages

A+ (programming language) A+ is a high-level, interactive, interpreted array programming language designed for numerically intensive applications, especially those found in financial applications. History In 1985, Arthur Whitney created the A programming language ...

* A^♯, an object-oriented functional programming language * A Sharp (.NET) (also written "A#"), a port of Ada to the Microsoft .NET Platform * BASIC A+

Other uses in computing

* A* search algorithm, a pathfinding algorithm * A-0 System, an early computer compiler * , the HTML element for an anchor tag * a, equivalent (qname) to the RDF Schema Property rdf:type * A level of web accessibility defined by the Web Content Accessibility Guidelines * The address record type of DNS, defined in RFC 1035

Mathematics and logic

* A

numerical digit A numerical digit (often shortened to just digit) or numeral is a single symbol used alone (such as "1"), or in combinations (such as "15"), to represent numbers in positional notation, such as the common base 10. The name "digit" origin ...

meaning ten in hexadecimal and other positional numeral systems with a radix of 11 or greater * Sometimes in

blackboard bold Blackboard bold is a style of writing Emphasis (typography), bold symbols on a blackboard by doubling certain strokes, commonly used in mathematical lectures, and the derived style of typeface used in printed mathematical texts. The style is most ...

represents the algebraic numbers (

\mathbb

) (U+1D538 in Unicode) *

Universal quantifier In mathematical logic, a universal quantification is a type of quantifier, a logical constant which is interpreted as "given any", "for all", "for every", or "given an arbitrary element". It expresses that a predicate can be satisfied by e ...

in symbolic logic (symbol ∀ or

\forall

, an inverted letter A) * Universal affirmative, one of the four types of

categorical proposition In logic, a categorical proposition, or categorical statement, is a proposition that asserts or denies that all or some of the members of one category (the ''subject term'') are included in another (the ''predicate term''). The study of arguments ...

in logic *

Mills' constant In number theory, Mills' constant is defined as the smallest positive real number ''A'' such that the floor function of the double exponential function : \left\lfloor A^ \right\rfloor is a prime number for all positive natural numbers ''n''. ...

is represented by the symbol ''A'' * Glaisher–Kinkelin constant is also often represented by the symbol ''A''

Other uses in science and technology

* A battery, a vacuum tube filament type battery * A battery (size), a standard battery size *

Anode An anode usually is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, which is usually an electrode of the device through which conventional current leaves the devic ...

, an electrode * A, historical symbol for chemical element

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

, currently Ar * The center of a hexagonal face of the

Brillouin zone In mathematics and solid state physics, the first Brillouin zone (named after Léon Brillouin) is a uniquely defined primitive cell in reciprocal space Reciprocal lattice is a concept associated with solids with translational symmetry whic ...

of a hexagonal lattice, in physics

Arts and media

Books

* "A", a poem by twentieth century author

Louis Zukofsky Louis Zukofsky (January 23, 1904 – May 12, 1978) was an American poet. He was the primary instigator and theorist of the so-called "Objectivist" poets, a short lived collective of poets who after several decades of obscurity would reemerge a ...

* '' a, A Novel'', by twentieth century artist Andy Warhol * A, the name of the Fourth Raikage, the leader of Kumogakure in the

Naruto ''Naruto'' is a Japanese manga series written and illustrated by Masashi Kishimoto. It tells the story of Naruto Uzumaki, a young ninja who seeks recognition from his peers and dreams of becoming the Hokage, the leader of his village. T ...

manga series * A (''Pretty Little Liars''), the main antagonist in the ''Pretty Little Liars'' book and TV series * A (for "adultery"), the titular letter in the novel ''

The Scarlet Letter ''The Scarlet Letter: A Romance'' is a historical novel by American author Nathaniel Hawthorne, published in 1850. Set in the Puritan Massachusetts Bay Colony during the years 1642 to 1649, the novel tells the story of Hester Prynne, who concei ...

'' * '' "A" Is for Alibi'', the first novel in Sue Grafton's "Alphabet mystery" series, published in 1982 *

Matthew Arnold Matthew Arnold (24 December 1822 – 15 April 1888) was an English poet and cultural critic. He was the son of Thomas Arnold, the headmaster of Rugby School, and brother to both Tom Arnold (academic), Tom Arnold, literary professor, and Willi ...

, who used the pseudonym "A" *

Isaac Asimov Isaac Asimov ( ; – April 6, 1992) was an Russian-born American writer and professor of biochemistry at Boston University. During his lifetime, Asimov was considered one of the "Big Three" science fiction writers, along with Robert A. H ...

, who used the pseudonym "Dr. A" *

Alexander Pope Alexander Pope (21 May 1688 Old Style and New Style dates, O.S. – 30 May 1744) was an English poet, translator, and satirist of the Age of Enlightenment, Enlightenment era who is considered one of the most prominent English poets of the early ...

, who used the pseudonym "A"

Film and TV

Films

* ''A'' (1965 film), a short film animated by Jan Lenica * ''A'' (1998 Kannada film), an Indian movie directed by Upendra * ''A'' (1998 Japanese film), a documentary film about a Buddhist sect called "A" * ''A'' (2002 film), a British documentary film

Film ratings

* A, a rating in India's

Central Board of Film Certification The Central Board of Film Certification (CBFC) is a statutory Motion picture content rating system, film-certification body in the Ministry of Information and Broadcasting (India), Ministry of Information and Broadcasting of the Government of ...

* A certificate, a film rating used by the

Canadian motion picture rating system Motion picture ratings in Canada are mostly a provincial responsibility, and each province has its own legislation regarding exhibition and admission. For home video purposes, a single Canadian Home Video Rating System rating consisting of an a ...

* A, a British Board of Film Classification rating used from 1912 to 1982, see History of British film certificates

Television

* CTV 2, a Canadian television system formerly known as A-Channel and A *A, the main antagonist and unknown character of the show ''

Pretty Little Liars ''Pretty Little Liars'' is an American Mystery fiction, mystery teen drama television series created by I. Marlene King, which aired on Freeform (TV channel), Freeform from June 8, 2010 to June 27, 2017, based on the novel series Pretty Little L ...

'' * "A" (''The Walking Dead''), an episode of the television series ''The Walking Dead'' *A, code name of Ange, the main protagonist of the anime show '' Princess Principal'' *"A"-logo for the Spanish network Antena 3. *A, the production code for the 1963 ''Doctor Who'' serial ''

An Unearthly Child ''An Unearthly Child'' (sometimes referred to as ''100,000 BC'') is the first serial of the British science fiction television series ''Doctor Who''. It was first broadcast on BBC One, BBC TV in four weekly parts from 23 November to 14 Decem ...

Music

A (musical note) A is a musical note equivalent to 440 Hz in typical A440 tuning. It is the sixth note of La and the tenth semitone of the fixed-do solfège. Its enharmonic equivalents are B (B double-flat) and G (G double-sharp). "A" is generally used a ...

, the sixth solfège note *

A major A major is a major scale based on A, with the pitches A, B, C, D, E, F, and G. Its key signature has three sharps. Its relative minor is F-sharp minor and its parallel minor is A minor. The A major scale is: Changes needed for the ...

, a scale *

A minor A minor is a minor scale based on A, B, C, D, E, F, and G. Its key signature has no flats or sharps. Its relative major is C major and its parallel major is A major. The A natural minor scale is: Changes needed for the melodic ...

, a scale * A major chord; see Chord names and symbols (popular music)

Performers

A (band) A are a British alternative rock band from Suffolk, England, which formed in 1993. They have released 4 studio and 2 live albums, including their debut '' How Ace Are Buildings'' and the UK top 20 album '' Hi-Fi Serious''. Single releases have ...

, a British alternative rock band

Albums

* ''A'' (Agnetha Fältskog album), 2013 * ''A'' (Cass McCombs album), 2003 * ''A'' (Jimmy Raney album), 1957 * ''A'' (Jethro Tull album), 1980 * ''A'' (Usher and Zaytoven album), 2018 * ''A'', a

Denki Groove is a Japanese music group founded in 1989. It consists of Takkyu Ishino and Pierre Taki. History Denki Groove was founded in 1989 by Takkyu Ishino and Pierre Taki, both of whom are natives of Shizuoka (city), Shizuoka, Shizuoka Prefecture. They ...

album (read as "Ace") * ''A'' (Ayumi Hamasaki EP), 1999 * ''A'' (single album), a 2015 single by the Korean band Big Bang * ''A!'' (album), by Alexa Feser, 2019 * ''A (album), by Afrirampo, 2004

Songs

* A or Side A, the top or first side of a

gramophone record A phonograph record (also known as a gramophone record, especially in British English) or a vinyl record (for later varieties only) is an analog sound storage medium in the form of a flat disc with an inscribed, modulated spiral groove. The g ...

* "A" (Rainbow song), a 2010 single by Rainbow * "A", song by A from '' 'A' vs. Monkey Kong'' * "A", song by Got7 from '' Got Love'' (2014) * "A", song by the band Barenaked Ladies from '' Maybe You Should Drive'' * "A", song by Cartel from '' Chroma'' * "A", a song in the Dance Dance Revolution video game series, by DJ Amuro

Other media

* /a/, the anime and manga section on 4chan * A, a Japanese video game rating in the Computer Entertainment Rating Organization suitable for all ages.

Geography

* Austria, on the vehicle registration plates of the European Union *"

The A ''The'' is a grammatical article in English, denoting nouns that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The ...

", a nickname for the U.S. city of Atlanta, Georgia

Linguistics

Letters

* A (or a), the first letter of the Latin alphabet * A (Indic), the many form of brahmic "a" * A (Bengali), the romanized name of the Bengali letter অ * A (cuneiform), the romanized name of a cuneiform sign *

A (Cyrillic) А (А а; italics: ''А а'') is a letter of the Cyrillic script. It commonly represents an open central unrounded vowel , halfway between the pronunciation of in "cat" and "father". The Cyrillic letter А is Romanization, romanized usin ...

(A or а), the first letter of the Cyrillic alphabet * A (kana) (or a), the romanized name of the Hiragana syllable letter あ and of the Katakana syllable letter ア used in Japanese, which may also be used to represent Asia *

Alpha Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ...

(Α or α), the first letter of the Greek alphabet

Other uses in linguistics

A and an The articles in English are the definite article '' the'' and the indefinite articles '' a'' and ''an''. They are the two most common determiners. The definite article is the default determiner when the speaker believes that the listener kn ...

, the indefinite article in English * A, a glossing abbreviation for agent-like argument of canonical transitive verb * , the IPA representation of the

open front unrounded vowel The open front unrounded vowel, or low front unrounded vowel, is a type of vowel sound used in some spoken languages. It is one of the eight primary cardinal vowels, not directly intended to correspond to a vowel sound of a specific language b ...

* , the IPA representation of the

open back unrounded vowel The open back unrounded vowel, or low back unrounded vowel, is a type of vowel sound, used in some Speech, spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is , and the equivalent X-SAMPA symbol is A ...

* ''a.'', an abbreviation of ''ante'' (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for "before") used in etymologies

People

* A (pharaoh), an Egyptian pharaoh * A Martinez, an American actor and singer *

, who used the pseudonym "A" *

, who used the pseudonym "Dr. A" *

, who used the pseudonym "A" *

Brfxxccxxmnpcccclllmmnprxvclmnckssqlbb11116 The naming law in Sweden (, alternately ) is a Judiciary of Sweden, Swedish law which requires the approval of the government agency for Swedish name, names to be given to Swedish children. The parents must submit the proposed name of a child with ...

, a Swedish child born in 1991, alternately called "A"

Philosophy and religion

* A, the Dominical letter of a

common year starting on Sunday A common year starting on Sunday is any non-leap year (i.e. a year with 365 days) that begins on Sunday, January 1, 1 January, and ends on Sunday, December 31, 31 December. Its dominical letter hence is A. The most recent year of such kind was 2023 ...

* Scarlet A, symbol for atheism adopted by the Out Campaign, a public awareness initiative proposed by Elizabeth Cornwell and Richard Dawkins * Alpha, (sometimes A) in

Christian theology Christian theology is the theology – the systematic study of the divine and religion – of Christianity, Christian belief and practice. It concentrates primarily upon the texts of the Old Testament and of the New Testament, as well as on Ch ...

, a metaphor for the beginning/creation of time and matter * An

anarchist symbol Anarchists have employed certain symbols for their cause since the 19th century, including most prominently the circle-A and the black flag. Anarchist cultural symbols have become more prevalent in popular culture since around the turn of the ...

, an A within a circle * The Gregory-Aland siglum for the

Codex Alexandrinus The Codex Alexandrinus (London, British Library, Royal MS 1. D. V-VIII) is a manuscript of the Greek Bible,The Greek Bible in this context refers to the Bible used by Greek-speaking Christians who lived in Egypt and elsewhere during the early ...

Transport

Automobile

* Ford Model A, a name used by two separate cars produced by the Ford Motor Company: ** Ford Model A (1903–04) ** Ford Model A (1927–31) * Geometry A, an electric mid-size sedan by Geely Auto

Rail

* A (S-train) a service on the S-train network in Copenhagen * Line A of the Buenos Aires Subte * Line A (Prague Metro) * Mexico City Metro Line A * NZR A class (disambiguation) two New Zealand steam locomotive classes * RER A, a line in the RER of Paris * Lyon Metro Line A *

Toei Asakusa Line The is a subway line in Tokyo, Japan, operated by the municipal subway operator Toei Subway. The line runs between in Ōta, Tokyo, Ōta and in Sumida, Tokyo, Sumida. The line is named after the Asakusa district, a cultural center of Tokyo, un ...

, a subway service operated by the Tokyo Metropolitan Bureau of Transportation (Toei), labeled Toei Asakusa line symbol

* The official West Japan Railway Company service symbol for: ** JRW kinki-A

Akō Line, Biwako Line, Kobe Line, Kyoto Line,

Hokuriku Main Line The Hokuriku Main Line () is a railway line owned by the West Japan Railway Company (JR West) connecting Maibara Station in Maibara, Shiga, with Tsuruga Station in Tsuruga, Fukui. The line formerly extended as far as Naoetsu Station in ...

, San'yō Main Line, and JR West Tōkaidō Line. ** JRW san-A

San'in Main Line The is a railway line in western Japan, which connects Kyoto and Shimonoseki, Yamaguchi, operated by West Japan Railway Company (JR West). It is the major railway line of the San'in region, approximately paralleling the Japan Sea, crossing Kyot ...

. * United States ** A (Los Angeles Railway) **

A (New York City Subway service) The A Eighth Avenue Express is a rapid transit service in the B Division (New York City Subway), B Division of the New York City Subway. Its route emblem, or "bullet", is colored since it is a part of the IND Eighth Avenue Line in Manhattan. ...

, also known as the "A Eighth Avenue Express" **

Alton Railroad The Alton Railroad was the final name of a railroad linking Chicago to Alton, Illinois; St. Louis, Missouri; and Kansas City, Missouri. Its predecessor, the Chicago and Alton Railroad , was purchased by the Baltimore and Ohio Railroad in 1931 an ...

(reporting mark) **

A Line (Los Angeles Metro) The A Line (formerly and colloquially known as the Blue Line) is a light rail line in Los Angeles County, California. It is one of the six lines of the Los Angeles Metro Rail system, operated by the Los Angeles County Metropolitan Transportati ...

* Britain ** LCDR A class, British 0-4-4T steam locomotives introduced in 1875 ** LD&ECR Class A, British 0-6-2T steam locomotives introduced in 1895 ** LNWR Class A, British 0-8-0 steam locomotives introduced in 1893 ** NER Class A, British 2-4-2T steam locomotives introduced in 1886 ** SER A class, British 4-4-0 steam locomotives introduced in 1879 ** Taff Vale Railway A class, British 0-6-2T steam locomotives introduced in 1914

Ships

* ''A'' (motor yacht) (M/Y ''A''), a 119m yacht owned by Andrey Melnichenko * ''A'' (sailing yacht) (S/Y ''A''), a 143m yacht owned by Andrey Melnichenko * , a Kaiserliche Marine tanker

Other uses

* A (grade), an academic grade * A series of paper sizes defined by

ISO 216 ISO 216 is an international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, which includes the A4, the most commonly availabl ...

, e.g. A4, A5 sizes * A formation, an American football offensive formation *

A-frame An A-frame is a basic structure designed to bear a Structural load, load in a lightweight economical manner. The simplest form of an A-frame is two similarly sized Beam (structure), beams, arranged in an angle of 45 degrees or less, attached a ...

, a type of structure *

Aalto University Aalto University (; ) is a public university, public research university located in Espoo, Finland. It was established in 2010 as a merger of three major Finnish universities: the Helsinki University of Technology, the Helsinki School of Economic ...

, public research university in Espoo, Finland * Ace, a playing card *

Agilent Technologies Agilent Technologies, Inc. is an American global company headquartered in Santa Clara, California, that provides instruments, software, services, and consumables for laboratories. Agilent was established in 1999 as a spin-off from Hewlett-Packar ...

, with U.S. ticker symbol A *

Sentinel Peak (Arizona) Sentinel Peak is a peak in the Tucson Mountains southwest of downtown Tucson, Arizona, United States. The valley's first inhabitants grew crops at the mountain's base, along the Santa Cruz River (Arizona), Santa Cruz River. The name "Tucson" ...

, more commonly known as "A" Mountain for the human-made rock formation in the shape of the letter * Alfa, the military time zone code for UTC+01:00 * Farmall A, a tractor produced by International Harvester from 1939 to 1947 * Oakland A's, or the Athletics, a professional baseball team based in Oakland, California, United States

Science and technology

Quantities and units

Astronomy

Biology

Computing

Programming languages

Other uses in computing

Mathematics and logic

Other uses in science and technology

Arts and media

Books

Film and TV

Films

Film ratings

Television

Music

Performers

Albums

Songs

Other media

Geography

Linguistics

Letters

Other uses in linguistics

People

Philosophy and religion

Transport

Automobile

Rail

Ships

Other uses

See also