F is the sixth letter of the Latin alphabet. F may also refer to:

Science and technology

Mathematics

* F or f, the number 15 in hexadecimal and higher positional systems * _''p''''F''_''q'', the hypergeometric function *

F-distribution In probability theory and statistics, the ''F''-distribution or F-ratio, also known as Snedecor's ''F'' distribution or the Fisher–Snedecor distribution (after Ronald Fisher and George W. Snedecor) is a continuous probability distribution th ...

, a continuous probability distribution **

F-test An ''F''-test is any statistical test in which the test statistic has an ''F''-distribution under the null hypothesis. It is most often used when comparing statistical models that have been fitted to a data set, in order to identify the model th ...

, a statistical test * f, SI prefix

femto 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 ...

, factor 10⁻¹⁵ * ,

Fibonacci number In mathematics, the Fibonacci numbers, commonly denoted , form a sequence, the Fibonacci sequence, in which each number is the sum of the two preceding ones. The sequence commonly starts from 0 and 1, although some authors start the sequence from ...

Computing and engineering

* F (programming language), a subset of Fortran 95 * F Sharp (programming language), a functional and object-oriented language for the .NET platform. *

F* (programming language) F* (pronounced ''F star'') is a functional programming language inspired by ML and aimed at program verification. Its type system includes dependent types, monadic effects, and refinement types. This allows expressing precise specifications fo ...

, a dependently typed functional language for the .NET platform. * F-measure, the harmonic mean of precision and recall * f, in programming languages often used to represent the

floating point In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can be ...

F connector The F connector (also F-type connector) is a coaxial RF connector commonly used for "over the air" terrestrial television, cable television and universally for satellite television and cable modems, usually with RG-6/U cable or with RG-59/U c ...

, used for inlet in cable modems *

F crimp F-Crimp is a type of solderless electrical crimp connection. It is not related to the F connector common in RF equipment. It is sometimes referred to as ''open-barrel'', which is technically a more general term including crimp types such as ''Weat ...

, a type of solderless electrical connection *

F band (NATO) The NATO F band is the obsolete designation given to the radio frequencies from 3 000 to 4 000 MHz (equivalent to wavelengths between 10 and 7.5 cm) during the cold war period. Since 1992 frequency allocations, allotment and assignments are ...

, a radio frequency band from 3 to 4 GHz *

F band (waveguide) The waveguide F band is the range of radio frequencies from 90 GHz to 140 GHz in the electromagnetic spectrum, corresponding to the recommended frequency band of operation of WR8 waveguides. These frequencies are equivalent to wave leng ...

, a millimetre wave band from 90 to 140 GHz

Physics

* °F, degree on the

Fahrenheit The Fahrenheit scale () is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accounts of how he originally defined his ...

temperature scale * F, for

farad The farad (symbol: F) is the unit of electrical capacitance, the ability of a body to store an electrical charge, in the International System of Units (SI). It is named after the English physicist Michael Faraday (1791–1867). In SI base unit ...

, a unit for electric capacitance * or ℱ, the

Faraday constant In physical chemistry, the Faraday constant, denoted by the symbol and sometimes stylized as ℱ, is the electric charge per mole of elementary charges. It is named after the English scientist Michael Faraday. Since the 2019 redefinition of S ...

* ,

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

of a lens **

f-number In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill ...

(sometimes called f-ratio, f-stop, or written f/), the focal length divided by the aperture diameter *

\vec F

, , ,

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

* ,

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

* F (or 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 In thermodynamics, an isotherma ...

* ''F'', the

electromagnetic field tensor In electromagnetism, the electromagnetic tensor or electromagnetic field tensor (sometimes called the field strength tensor, Faraday tensor or Maxwell bivector) is a mathematical object that describes the electromagnetic field in spacetime. Th ...

in electromagnetism *: Often generalized to include the field tensors of other interactions, as in i.e. the

gluon field strength tensor In theoretical particle physics, the gluon field strength tensor is a second order tensor field characterizing the gluon interaction between quarks. The strong interaction is one of the fundamental interactions of nature, and the quantum fie ...

. *

F region The F region of the ionosphere is home to the F layer of ionization, also called the Appleton–Barnett layer, after the English physicist Edward Appleton and New Zealand physicist and meteorologist Miles Barnett. As with other ionospheric sectors ...

, part of the ionosphere

Chemistry

Fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

, symbol F, a chemical element *

f-block A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-bloc ...

, a block of elements in the periodic table of elements * F (or Phe), abbreviation for compound

phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amino a ...

Biology

Form (botany) In botanical nomenclature, a ''form'' (''forma'', plural ''formae'') is one of the "secondary" taxonomic ranks, below that of variety, which in turn is below that of species; it is an infraspecific taxon. If more than three ranks are listed in ...

Form (zoology) In zoology, the word "form" or ''forma'' (literally Latin for form) is a strictly informal term that is sometimes used to describe organisms. Under the ''International Code of Zoological Nomenclature'' the term has no standing (it is not accepted). ...

Bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

, which is expressed as the letter "F" in medical chemistry equations *

Haplogroup F (Y-DNA) Haplogroup F, also known as F-M89 and previously as Haplogroup FT is a very common Y-chromosome haplogroup. The clade and its subclades constitute over 90% of paternal lineages outside of Africa. The vast majority of individual males with F-M89 ...

, a patrilineal haplogroup *

Haplogroup F (mtDNA) Haplogroup F is a human mitochondrial DNA (mtDNA) haplogroup. The clade is most common in East Asia and Southeast Asia.Supannee Kaewsutthi, Nopasak Phasukkijwatana, Yutthana Joyjinda ''et al.'', "Mitochondrial Haplogroup Background May Influence ...

, a matrilineal haplogroup

Music

F (musical note) F is a musical note, the fourth above C or fifth below C. It is the fourth note and the sixth semitone of the solfège. It is also known as fa in fixed-do solfège. It has enharmonic equivalents of E (E-sharp) and G (G-double flat), amongst o ...

F major F major (or the key of F) is a major scale based on F, with the pitches F, G, A, B, C, D, and E. Its key signature has one flat. Its relative minor is D minor and its parallel minor is F minor F minor is a minor scale based on F, consis ...

, a scale *

F minor F minor is a minor scale based on F, consisting of the pitches F, G, A, B, C, D, and E. Its key signature consists of four flats. Its relative major is A-flat major and its parallel major is F major. Its enharmonic equivalent, E-sharp mi ...

, a scale * F major chord,

Chord names and symbols (popular music) Musicians use various kinds of chord names and symbols in different contexts to represent musical chords. In most genres of popular music, including jazz, pop, and rock, a chord name and its corresponding symbol typically indicate one or more ...

* f,

Forte (music) In music, the dynamics of a piece is the variation in loudness between notes or phrases. Dynamics are indicated by specific musical notation, often in some detail. However, dynamics markings still require interpretation by the performer dependi ...

* ''F'' (album), an album by Japanese singer Masaharu Fukuyama *''

F Album ''F Album'' is the sixth studio album of the Japanese duo KinKi Kids. It was released on December 26, 2002 and debuted at number two on the Oricon charts, selling 360,102 copies in its first week. The album was certified platinum by the RIAJ ...

'', an album by Japanese duo KinKi Kids *"F", song on the double A-side single "

Tsume Tsume Tsume/F is a double A-side maxi single by Japanese metal band Maximum the Hormone, released on July 9, 2008. The single reached number 2 on the Oricon Singles Chart and was certified gold by the RIAJ. The tracks "Tsume Tsume Tsume" and "F" were include ...

" by Japanese metal band Maximum the Hormone

Transport

* F Sixth Avenue Local, a rapid transit service of the New York City Subway *

F (S-train) F is the service designation for trains on the ring line of Copenhagen's S-train network. It runs from about 05:00 to 01:00 from Ny Ellebjerg to Hellerup. Trains run every 5 minutes between about 7:00 and 19:00, Monday through Friday, and ever ...

, trains on the ring line of Copenhagen's commuter train network *

F Market & Wharves The F Market & Wharves line is one of several light rail lines in San Francisco, California. Unlike most other lines in the system, the F line runs as a heritage streetcar service, almost exclusively using historic equipment both from San Franc ...

, a heritage streetcar line operated by the San Francisco Municipal Railway * The NYSE ticker symbol of the

Ford Motor Company Ford Motor Company (commonly known as Ford) is an American multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. The company sells automobi ...

Ford F-Series The Ford F-Series is a series of light-duty trucks marketed and manufactured by Ford since the 1948 model year. Slotted above the Ford Ranger in the Ford truck model range, the F-Series is marketed as a range of full-sized pickup trucks. ...

, a series of full-size pickup trucks from Ford Motor Company

Military

* F, a class of designation in the

United States military aircraft designation systems Multiple designation systems have been used to specify United States military aircraft. The first was designed in 1919 when the US Army's Aeronautical Division became the United States Army Air Service. Before this, aircraft were put into service un ...

which stands for "Fighter" * F, a common designation for

fighter aircraft Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...

Foxtrot The foxtrot is a smooth, progressive dance characterized by long, continuous flowing movements across the dance floor. It is danced to big band (usually vocal) music. The dance is similar in its look to waltz, although the rhythm is in a tim ...

, the military time zone code for UTC+06:00 *

, a radio frequency band from 3 to 4 GHz

Other uses

* ''F'' (film), a 2010 film directed by Johannes Roberts *

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, on the

vehicle registration plates of the European Union A vehicle registration plate, also known as a number plate (British English), license plate or licence plate (American English and Canadian English respectively), is a metal or plastic plate or plates attached to a motor vehicle or trailer for of ...

F (grade) This is a list of Grading (education)#International grading systems, grading systems used by countries of the world, primarily within the fields of secondary education and university education, organized by continent with links to specifics in num ...

, a failing grade * f, the symbol used in the International Phonetic Alphabet for the

voiceless labiodental fricative The voiceless labiodental fricative is a type of consonantal sound used in a number of spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is . Some scholars also posit the voiceless labiodental approx ...

* f, common abbreviation in lexicons meaning ''feminine

grammatical gender In linguistics, grammatical gender system is a specific form of noun class system, where nouns are assigned with gender categories that are often not related to their real-world qualities. In languages with grammatical gender, most or all nouns ...

'' *

Fax Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...

, referring to a facsimile machine * F, abbreviation for

fax number Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephone, telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a ...

* The citation abbreviation of the ''

Federal Reporter The ''Federal Reporter'' () is a case law reporter in the United States that is published by West Publishing and a part of the National Reporter System. It begins with cases decided in 1880; pre-1880 cases were later retroactively compiled by We ...

'' * F,

Fujitsu is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...

's mobile phones in Japan *

Forward Forward is a relative direction, the opposite of backward. Forward may also refer to: People * Forward (surname) Sports * Forward (association football) * Forward (basketball), including: ** Point forward ** Power forward (basketball) ** Sm ...

position in Australian Rules football * "F" or "F***", sometimes used to censor "

fuck ''Fuck'' is an English-language expletive. It often refers to the act of sexual intercourse, but is also commonly used as an intensifier or to convey disdain. While its origin is obscure, it is usually considered to be first attested to aro ...

". * f, abbreviation for the social networking service

Facebook Facebook is an online social media and social networking service owned by American company Meta Platforms. Founded in 2004 by Mark Zuckerberg with fellow Harvard College students and roommates Eduardo Saverin, Andrew McCollum, Dustin M ...

* Common abbreviation for

floor A floor is the bottom surface of a room or vehicle. Floors vary from simple dirt in a cave to many layered surfaces made with modern technology. Floors may be stone, wood, bamboo, metal or any other material that can support the expected load ...

(for example, "3F" = 3rd floor) *

F word (disambiguation) F Word or The F Word may refer to: *Any of several words that begins with the letter " f", often used as a euphemism where they may be considered controversial, particularly: **Fuck ** Faggot (slang) Film and television * ''The F Word'' (Bri ...

, euphemism for several words beginning with "f" * Dominical letter F for a

common year starting on Tuesday A common year starting on Tuesday is any non-leap year (i.e. a year with 365 days) that begins on Tuesday, 1 January, and ends on Tuesday, 31 December. Its dominical letter hence is F. The most recent year of such kind was 2019 and the next one wi ...

* F, as an online expression of respects to a recently deceased person (as a reference to the videogame '' Call of Duty: Advanced Warfare'') *F, the production code for the 1964 ''Doctor Who'' serial ''

The Aztecs The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl ...

'' * ''

"F" Is for Fugitive ''"F" Is for Fugitive'' is the sixth novel in Sue Grafton's "Alphabet" series of mystery novels and features Kinsey Millhone, a private eye based in Santa Teresa, California. Plot summary Henry Pitts is having Kinsey's garage apartment rebuilt af ...

'', the sixth novel in Sue Grafton's "Alphabet mystery" series, published in 1989