As the Proto-Indo-European language (PIE) broke up, its sound system diverged as well, as evidenced in various sound laws associated with the daughter

Indo-European languages The Indo-European languages are a language family native to the overwhelming majority of Europe, the Iranian plateau, and the northern Indian subcontinent. Some European languages of this family, English, French, Portuguese, Russian, ...

. Especially notable is the palatalization that produced the

satem language Languages of the Indo-European family are classified as either centum languages or satem languages according to how the dorsal consonants (sounds of "K", "G" and "Y" type) of the reconstructed Proto-Indo-European language (PIE) developed. An e ...

s, along with the associated ruki sound law. Other notable changes include: * Grimm's law and Verner's law in Proto-Germanic * an independent change similar to Grimm's law in Armenian * loss of prevocalic ''*p-'' in Proto-Celtic *

Brugmann's law Brugmann's law, named for Karl Brugmann, is a sound law stating that in the Indo-Iranian languages, the earlier Proto-Indo-European ' normally became in Proto-Indo-Iranian but in open syllables if it was followed by one consonant and another vow ...

Proto-Indo-Iranian Proto-Indo-Iranian, also Proto-Indo-Iranic is the reconstructed proto-language of the Indo-Iranian/Indo-Iranic branch of Indo-European. Its speakers, the hypothetical Proto-Indo-Iranians, are assumed to have lived in the late 3rd millennium B ...

* Winter's law and Hirt's law in Balto-Slavic * merging of voiced and breathy-voiced stops, and /a/ and /o/, in various "northern" languages

Bartholomae's law Bartholomae's law (named after the German Indo-Europeanist Christian Bartholomae) is an early Indo-European (PIE) sound law affecting the Indo-Iranian family. It states that in a cluster of two or more obstruents (stops or the sibilant ), any one ...

in Indo-Iranian, and

Sievers's law Sievers's law in Indo-European studies, Indo-European linguistics accounts for the pronunciation of a consonant cluster with a glide ( or ) before a vowel as it was affected by the phonetics of the preceding syllable. Specifically it refers to ...

in Proto-Germanic and (to some extent) various other branches, may or may not have been common Indo-European features. A number of innovations, both phonological and morphological, represent areal features common to the Italic and Celtic languages; among them the development of labiovelars to labial consonants in some Italic and Celtic branches, producing " p-Celtic" and " q-Celtic" languages (likewise "p-Italic" and "q-Italic", although these terms are less used). Another grouping with many shared areal innovations comprises Greek, Indo-Iranian, and Armenian; among its common phonological innovations are Grassmann's law in Greek and Indo-Iranian, and weakening of pre-vocalic /s/ to /h/ in Greek, Iranian and Armenian.

Consonants

The following table shows the Proto-Indo-European consonants and their

reflexes In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a Stimulus (physiology), stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous s ...

in selected Indo-European daughter languages. Background and further details can be found in various related articles, including

Proto-Indo-European phonology The phonology of the Proto-Indo-European language (PIE) has been reconstructed by linguists, based on the similarities and differences among current and extinct Indo-European languages. Because PIE was not written, linguists must rely on the evi ...

, Centum and satem languages, the articles on the various sound laws referred to in the introduction, and the articles on the various IE proto-languages, language groups and language phonologies. For development of the laryngeals and syllabic consonants, see the vowels table below. Notes for table 1:

Consonant clusters

Proto-Indo-European also had numerous

consonant cluster In linguistics, a consonant cluster, consonant sequence or consonant compound, is a group of consonants which have no intervening vowel. In English, for example, the groups and are consonant clusters in the word ''splits''. In the education f ...

s, such as , . In most cases in most languages, each consonant in a cluster develops according to the normal development given in the table above. Many consonant clusters however also show special developments in multiple languages. Some of these are given by the following table (with cases of otherwise predictable development in gray): Notes to Table 2:

Vowels and syllabic consonants

This table shows the Proto-Indo-European vowels and

syllabic consonant A syllabic consonant or vocalic consonant is a consonant that forms a syllable on its own, like the ''m'', ''n'' and ''l'' in some pronunciations of the English words ''rhythm'', ''button'' and ''bottle''. To represent it, the understroke diacrit ...

s (as reconstructed both before and after the acceptance of laryngeal theory), and their

in selected Indo-European daughter languages. Background and further details can be found in various related articles, including

, the articles on the various sound laws referred to in the introduction, and the articles on the various IE proto-languages, language groups and language phonologies. Notes:

Examples

See the list of Proto-Indo-European roots hosted at Wiktionary.

, ~ , "foot". * Vedic Sanskrit: ''pā́t'', ''pád-'' *

Avestan Avestan (), or historically Zend, is an umbrella term for two Old Iranian languages: Old Avestan (spoken in the 2nd millennium BCE) and Younger Avestan (spoken in the 1st millennium BCE). They are known only from their conjoined use as the scrip ...

: ''paδa'', ''pāδa'' *

Old Church Slavonic Old Church Slavonic or Old Slavonic () was the first Slavic languages, Slavic literary language. Historians credit the 9th-century Byzantine Empire, Byzantine missionaries Saints Cyril and Methodius with Standard language, standardizing the lan ...

: ''pěšĭ'', "on foot" *

Lithuanian Lithuanian may refer to: * Lithuanians * Lithuanian language * The country of Lithuania * Grand Duchy of Lithuania * Culture of Lithuania * Lithuanian cuisine * Lithuanian Jews as often called "Lithuanians" (''Lita'im'' or ''Litvaks'') by other Jew ...

: ''pėda'', "foot bottom" * Armenian: ''otn'' * Tocharian: A ''pe'', B ''pai'' * Luwian: ''pa-da-'', ''pa-ta-'' *

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

: ''poús'', ''podós'' *

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

: ''pēs'', ''pedis'' * Celtiberian: ''ozas'' *

Gothic Gothic or Gothics may refer to: People and languages *Goths or Gothic people, the ethnonym of a group of East Germanic tribes **Gothic language, an extinct East Germanic language spoken by the Goths **Crimean Gothic, the Gothic language spoken b ...

: ''fotus'' (*p -> f by Grimm's Law)

, "three". * Vedic Sanskrit: ''tráyas'' *

: ''θrāiiō'' *

: ''trĭje'' *

: ''trỹs'' *

Albanian Albanian may refer to: *Pertaining to Albania in Southeast Europe; in particular: **Albanians, an ethnic group native to the Balkans **Albanian language **Albanian culture **Demographics of Albania, includes other ethnic groups within the country ...

: ''tre'' *

: ''treĩs'' *

: ''trēs'' * Old Irish: ''trí'' *

Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peopl ...

: ''tri'' * Armenian: ''erekʿ'' *

: ''þreis'' (*t -> þ by Grimm's Law)

, "hundred" (from earlier ) * Vedic Sanskrit: ''śatám'' *

Younger Avestan Avestan (), or historically Zend, is an umbrella term for two Old Iranian languages: Old Avestan (spoken in the 2nd millennium BCE) and Younger Avestan (spoken in the 1st millennium BCE). They are known only from their conjoined use as the scrip ...

: ''satəm'' *

: ''sŭto'' *

Lithuanian Lithuanian may refer to: * Lithuanians * Lithua