As the Proto-Indo-European language (PIE) broke up, its sound system diverged as well, according to various sound laws in the daughter languages.

Notable among these are Grimm's law in Proto-Germanic, loss of prevocalic *p- in Proto-Celtic, loss of prevocalic *s- in Proto-Greek, Brugmann's law in Proto-Indo-Iranian. Grassmann's law and Bartholomae's law may or may not have been still common Indo-European.

Note - these draught tables need to be completed, verified, and the allophones explained.

Consonants

|; ²

|; ³; ⁴

!

|; ⁵

|; ³; ⁴

!

|; ⁵; ⁶

|; ³; ⁴

!

|; ³

!

|; ¹³

!

Proto-Indo-European consonants and their reflexes in the Indo-European daughter languages

Trad. PIE	Glot. PIE	Sanskrit	Avestan	O.C.S.	Lithuanian	Armenian	Albanian	Tocharian	Hittite	Greek	Latin	Old Irish	Proto-Germ.	English
						; 1						; 8; 4
							; 5			; 8	; 3; 4
						; 9	; 9				; 8	; 3; 4	; 8; 3; 4
		; 5	; 5	; 5; 10
								; 5; 10		; 7	; 8	; 3; 4
							; 8	; 5				; 8
							; 9	; 9				; 8		; 10
		; 5	; 5	; 5; 10
							; 5; 10			; 5; 6	; 15	; 8
						; 8					; 8	; 8		; 8
								; 5			; 8; 14	; 8
						; 8	; 9	; 5			; / 9	; 5		; 8
		; 5	; 5	; 5; 10		; 5
							; 5; 10			; 5; 6	; / 8; 15			/ ; 8
		; 11	; 2; 11	; 11	; 11	; 2; 8	; 12	;		; 2; 8	; 8		; 8; 3
			; 13	; 13	; 13	; 13	; 13	; 13	; 13		; 8; 13
							;
		(dial. )				,	; 8
							;			/ ; 8	; 8
						/						; / 8
Trad. PIE	Glot. PIE	Sanskrit	Avestan	O.C.S.	Lithuanian	Armenian	Albanian	Tocharian	Hittite	Greek	Latin	Old Irish	Proto-Germ.	English

Notes:

• ¹ After vowels.
• ² Before a plosive ().
• ³ Before an unstressed vowel (Verner’s Law).
• ⁴ After a (Proto-Germanic) fricative ().
• ^{5 Before a (PIE) front vowel ().}
• ^{6 Before or after a (PIE) .}
• ^{7 Before or after a (PIE) .}
• ^{8 Between vowels.}
• ^{9 Before a resonant.}
• ^{10 Before secondary (post-PIE) front-vowels.}
• ^{11 After (RUKI).}
• ^{12 Before a stressed vowel.}
• ^{13 At the end of a word.}
• ^{14 After or before .}
• ^{15 After .}

Vowels and syllabic consonants

|; ¹⁰

!rowspan=3|

|; ⁸

|; ⁸

!

|; ¹¹

|; ¹

|; ²

!rowspan=3|

|; ¹⁴

!

|; ¹⁴

!

|; ¹⁴

|; ¹⁴

!|

|; ¹⁴

!|

|; ¹⁴

|; ¹⁴

!|

|; ¹³

|; ¹⁴

!|

|; ¹³

|; ¹⁴

!|

|; ¹⁴

!|

|; ¹³

|; ¹⁴

!|

|; ¹³

|; ¹⁴

Proto-Indo-European vowels and syllabic consonants, and their reflexes in the Indo-European daughter languages

Old reconstr.	New reconstr.	Sanskrit	Avestan	O.C.S.	Lithuanian	Armenian	Albanian	Tocharian	Hittite	Greek	Latin	Proto-Celtic	Gothic
							; 12						; 2
	( 3)
		, 4	, 4
								?; ? 8
	( 3)							?
								?; ? 8				; 8
						or ? 7			or ? 7
									or ? 7
				, 4		, 5					, 6
					, 5
	( 3)
		; 8	; 8								?
										8
					; 8
						or ? 7			or ? 7
									or ? 7
			, 4									; 9
	( 3)
											?
Old reconstr.	New reconstr.	Sanskrit	Avestan	O.C.S.	Lithuanian	Armenian	Albanian	Tocharian	Hittite	Greek	Latin	Old Irish	Gothic

Notes:

• ¹ Before wa.
• ² Before r, h.
• ³ The existence of PIE non-allophonic a is disputed.
• ⁴ In open syllables (Brugmann's law).
• ⁵ Under stress.
• ⁶ Before palatal consonants.
• ⁷ The so-called breaking is disputed (typical examples are > Ved. prátīkam ~ Gk. ; > Ved. jīvá- ~ Arm. keank‘, Gk. ; > Ved. dūrá- ~ Arm. erkar, Gk. )
• ⁸ In a final syllable.
• ⁹ Before velars and unstressed
• ¹⁰ Before ā in the following syllable.
• ¹¹ Before i in the following syllable.
• ¹² In a closed syllable.
• ¹³ In the neighbourhood of labials.
• ¹⁴ In the neighbourhood of labiovelars.

See also

---

• Centum-Satem isogloss
• Balto-Slavic
• Italo-Celtic
• Proto-Indo-Iranian
• Proto-Greek
• Proto-Celtic
• Proto-Germanic

Indo-European linguistics | Sound laws