Indo-European sound laws

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

Especially notable is the palatalization that produced the satem languages, 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 in Proto-Indo-Iranian
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 in Indo-Iranian, and Sievers’s law 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 selected Indo-European daughter languages. Background and further details can be found in various related articles, including Proto-Indo-European phonology, 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.

Table 1. Reflexes of Proto-Indo-European single consonants
PIE	Indo-Iranian		Balto-Slavic		Alb.	Arm.	Anatol.	Toch.	Greek		Italic	Celtic		Germanic
	Skr.	Av.	O.C.S.	Lith.			Hitt.		Greek		Latin	Old Irish		Gothic	English
	Skr.	Av.	O.C.S.	Lith.			Hitt.		normal	C+	Latin	normal	-C-	Gothic	English
*p	p; ph	p; f	p			h; w	p, pp	p		pt	p	∅		f; b	f; v, f
*t	t; th	t; θ	t			tʿ	t, tt; z	t; c	t	s; tt/ss	t	t	th	þ ; d ;	th; d;
*ḱ	ś	s		š	th ; k	s	k, kk	k; ś	k		c	c	ch	h; g	h; ∅; y
*k	k; c ; kh	k; c ; x	k; č ; c	k	k	kʿ	k, kk		k		c			h; g	h; ∅; y
*kʷ	k; c ; kh	k; c ; x	k; č ; c	k	k; s; q	kʿ	ku, kku		p; t; k		qu ; c			ƕ ; gw, w	wh; w
*b	b; bh	b; β	b			p			b	pt	b	b	—	p
*d	d; dh	d; δ	d		d; dh	t		ts; ś	d	z >	d	d	—	t
*ǵ	j ; h	z		ž	dh ; g	c	k	k; ś	g		g	g	—	k	c / k; ch
*g	g; j ; gh; h	g; j ; γ	g; ž ; dz	g	g	k	k		g		g	g	—	k	c / k; ch
*gʷ	g; j ; gh; h	g; j ; γ	g; ž ; dz	g	g; z; gj	k	ku		b; d; g		u ; gu	b	—	q	qu
*bʰ	bh	b; β	b			b; w	p		ph	pt	f; b	b	—	b ; b ; f	b; v / f
*dʰ	dh	d; δ	d				t	t; c	th	tt/ss	f; d; b	d	—	d; d ; þ	d
*ǵʰ	h	z		ž	dh ; d	j ; z	k	k; ś	kh		h; h / g	g	—	g; g ; g	g; y / w
*gʰ	gh ; h	g; j ; γ	g; ž ; dz	g	g	g; ǰ	k		kh		h; h / g			g; g ; g	g; y / w
*gʷʰ	gh ; h	g; j ; γ	g; ž ; dz	g	g; z; gj	g; ǰ	ku		ph ; th ; kh		f; g / u ; gu			g; b; w; gw	g; b; w
*s	s	h	s		sh ; gj ; h	h; ∅	š	s; ṣ	h; s;/ ∅;	i	s; r	s ʃ	—	s; z	s; r
*s	ṣ	š	x	š	sh ; gj ; h	h; ∅	š	s; ṣ	h; s;/ ∅;	i	s; r	s ʃ	—	s; z	s; r
*m	m									in	m	m	—	m
*-m	m		˛	n		∅	n	n		—	m	n		∅
*n	n		n; ˛	n				n; ñ	n	in	n
*l	r (dial. l)	r	l		l; ll	l / ɫ [ɫ > ɣ]	l			il	l
*r	r				r ; rr	r				ir	r
*y	y		j		gj ; ∅	∅	y		z > / h; ∅	?i	i ; ∅	∅		j	y
*w	v	v	v	v	v	g / w	w		w > h / ∅	i	u	f	–∅–	w
PIE	Skr.	Av.	O.C.S.	Lith.	Alb.	Arm.	Hitt.	Toch.	Greek	Greek+/j/	Latin	Old Irish		Gothic	English

Notes for table 1:

^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t Between vowels
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h Before an original h₂.
^ Jump up to:^a ^b ^c Before a consonant or original laryngeal.
^ Jump up to:^a ^b After a vowel.
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ Following an unstressed vowel (Verner’s law).
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u Before a (PIE) front vowel (*i, *e).
^ Jump up to:^a ^b ^c ^d ^e ^f Before a sonorant.
^ Jump up to:^a ^b ^c ^d ^e ^f ^g Before secondary (post-PIE) front-vowels.
^ Jump up to:^a ^b ^c Before or after a (PIE) u
^ Before or after a (PIE) rounded vowel (*u, *o).
^ Jump up to:^a ^b ^c ^d ^e ^f In Younger Avestan, after a vowel.
^ Jump up to:^a ^b ^c After n.
^ Jump up to:^a ^b ^c ^d ^e ^f At the beginning of a word
^ Jump up to:^a ^b ^c ^d ^e ^f At the end of a word.
^ Jump up to:^a ^b Between vowels, or between a vowel and r, l (on either side)
^ After u, r or before r, l.
^ Before a stressed vowel
^ Before or after an obstruent (p, t, k, etc.; s)
^ Before or after a resonant (r, l, m, n).
^ Jump up to:^a ^b ^c ^d After r, u, k, i (Ruki sound law).

Consonant clusters

Proto-Indo-European also had numerous consonant clusters, such as *st, *ḱs. 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):

This section needs expansionwith: thorn clusters, *sD, *sR, ? *ts, ? Bartholomae’s law. You can help by adding to it. (August 2016)

Table 2. Reflexes of Proto-Indo-European consonant clusters
PIE	Indo-Iranian		Balto-Slavic		Alb.	Arm.	Anatol.	Toch.	Greek		Italic	Celtic	Germanic
	Skr.	Av.	O.C.S.	Lith.			Hitt.		Greek		Latin	Old Irish	Gothic	English
	Skr.	Av.	O.C.S.	Lith.			Hitt.		normal	C+	Latin	Old Irish	Gothic	English
*sr	sr	r	str	sr	rr	(a)r	š(ša)r ʃʃr		rh	n/a	fr-, -br-	sr	str	str
*tw	tv	θβ	tv	tv	t	kʿ	ttu, ddu		s-, -ss-	n/a	p?	t	þw	thw
*dʰw	dhv	ðβ	dv	dv	d	?	tu, du				f	d	dw	dw
*dw	dv	ðβ	dv	dv	d	(e)rk	tu, du				b	d	tw	tw
*ḱw	śv	sp	sv	šv	s	sk, š				n/a	qu	cu	ƕ	wh
*ǵʰw	hv		zv	žv	z
*ǵw	jv		zv	žv	z								q	qu
*sw	sv	xuu	sv	sv	v	kʿ	normal dev.		h	n/a	su	s	sw	sw
*sp	sp	sp	sp		f	sp / pʿ	normal dev.		sp	?	sp	f	sp
*st	st	st	st		sht	st	normal dev.		st	s; tt/ss	st		st
*sḱ	ch ; cch	s?	sk	š?	h	?? č`; c`	normal dev.		sk; kh ; skh		sc	sc	sk	sh
*sk	sk, sc	sk, sč	normal dev.		?	sk	normal dev.		sk; kh ; skh		sc		sk
*skʷ	sk, sc	sk, sč	normal dev.		?	sk	normal dev.		norm.		squ		sq
*t+t	tt; tth	st; sθ?	st		s	s?	zt, zzašt, zzazz	ss?	st		ss		ss / st
*pt	pt	ft	t?	pt	t				pt		pt	cht	ft
*ḱt	ṣṭ	št	st	št					kt		ct		ht	ght
*kt	kt	xt	t?	kt					kt		ct
*kʷt	kt	xt	t?	kt					pt		ct
*ps									ps		ps	s, ss	fs	ps
*ḱs	kṣ	š			sh				ks		x		hs	x
*ks	kṣ	xš						(ks)	ks		x		hs
*kʷs	kṣ	xš					kʷs		ps		x
*sd	ḍ	zd	zd	zd		st					d	-t-	st	st
*sdʰ	ḍh	zd	zd	zd	Show side				sth			-t-	zd	d

Notes to Table 2:

^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ In contrast to *s normally giving h in Avestan, Armenian and Greek.
^ Jump up to:^a ^b ^c ^d ^e ^f ^g Germanic spirant law: *p, *t, *k, *kʷ remain stops when preceded by another stop or *s.
^ Jump up to:^a ^b ^c Between vowels.
^ After r, l, m, n, t, d, possibly other consonants?
^ After (Greek) th.
^ Before an original laryngeal.
^ Before a consonant or original laryngeal.
^ Jump up to:^a ^b After r, u, k, i (Ruki sound law).

Vowels and syllabic consonants

This table shows the Proto-Indo-European vowels and syllabic consonants (as reconstructed both before and after the acceptance of laryngeal theory), and their reflexes in selected Indo-European daughter languages. Background and further details can be found in various related articles, including Proto-Indo-European phonology, 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.

Trad. PIE	Laryng. PIE	Skr.	Av.	O.C.S.	Lith.	Arm.	Alb.	Toch.	Hitt.	Greek	Latin	Proto-Celtic	Gothic	Old English
Trad. PIE	Laryng. PIE	Skr.	Av.	O.C.S.	Lith.	Arm.	Alb.	Toch.	Hitt.	Greek	Latin	Proto-Celtic	Gothic	normal	umlauted
*e	e, h₁e	a		e			je, ie, e, i; ja	ä	e, ʔe, i	e			i; aí	e; eo	i; ie
*a	(a), h₂e			o	a	a	ha, a	ā	ha, a	a			a	æ; a;ea	e; ie
*o	*h₃e					o, a	a	a, e	a	o
*o	*o	a; ā				o, a		a, e	a	o
*ə	*h₁	i	i, ∅	∅		a, ∅		ā	∅	e	a		a, ∅
	*h₂								ḫ	a
	*h₃								∅	o
*-	*h₁-	∅				e (a?)	∅		a, ∅	e (o)	∅
	*h₂-					a			ḫa	a
	*h₃-					a			a, ha	o
*ē	ē, eh₁	ā		ě	ė	i	o, ua	a/e?; ā?	ē, e, i	ē		ī	ē	ǣ
*ā	(ā), eh₂			a	o	a	o, ua	a/o?	a, ah	ā > ē	ā	ā	ō		ē
*ō	ō, eh₃			a	uo	u	e	a/ā?; ū?	a, ā	ō		ā; ū	ō		ē
*i	*i	i		ь	i	i	i; e	ä	i, ī	i			i; aí	i
*ī	*ih₁	ī		i	y	i	i	i		ī	ī		ei	ī
	*ih₂					i or ^(j)a?		yā		ī or ^(j)ā?
	*ih₃					i or ^(j)a?		yā		ī or ^(j)ō?
*ei	ei, h₁ei	ai > ē	ai > ōi, āi > aē		ei; ie	i		e	ē	ei	ī	īa; ē
*oi	oi, h₃ei			ě	ai; ie	e	e, ai		ē, ai	oi	ū	oe	ái	ā	ǣ
*ai	(ai), h₂ei			ě	ai; ie	e	e, ai		ē, ai	ai	ae	ae	ái	ā	ǣ
*ēi	*ēi	ai; ā	āi; ā(i)	i			i		ē	ēi	ī?		ei	ī
*ōi	ōi (oei)			y; u	ai; ui		e, ai		ai	ōi	ō	u	ái	ā	ǣ
*āi	*eh₂ei			ě			e, ai		ai	āi > ēi	ae		ái	ā	ǣ
*u	*u	u		ъ	u	u	u; y	ä	u	u	u	u; o	u; aú	u; o	y
*ū	*uh₁	ū		y	ū	u	y; i	u		ū	ū				ȳ
	*uh₂					u or ^(w)a?		wā		ū or ^(w)ā?
	*uh₃					u or ^(w)a?		wā		ū or ^(w)ō?
*eu	eu, h₁eu	ō	ə̄u; ao	ju	iau	oy	e	u		eu	ū	ūa; ō	iu	ēo	īe
*ou	ou,h₃eu			u	au	oy	a	o, au		ou	ū		áu	ēa
*au	(au), h₂eu			u	au	aw	a	o, au		au	au		áu	ēa
*ēu	*ēu	āu		u	iau		e				ū?		iu	ēo
*ōu	*ōu	āu					a		au	ō			áu	ēa
*m̥	*m̥	a		ę	im̃; um̃	am	a	äm	a, un	a	em	em, am	um	um	ym
*m̥̅	*mh₁	ā			ìm; ùm	ama		mā		mē	mā
	*mh₂									mā > mē
	*mh₃									mō
*m̥m	*m̥m	am		ьm/ъm	im; um	am				am	em	am
*n̥	*n̥	a		ę	iñ; uñ	an		än	an	a	en	en, an	un	un	yn
*n̥̄	*nh₁	ā			ìn; ùn	ana		nā		nē	nā
	*nh₂									nā > nē
	*nh₃									nō
*n̥n	*n̥n	an		ьn/ъn	iñ; uñ	an				an	en	an
*l̥	*l̥	ṛ	ərə	lь/lъ	il̃; ul̃	al	il, li; ul, lu	äl	al	la	ol	li;al	ul	ul; ol	yl
*l̥̄	*lh₁	īr; ūr	arə		ìl; ùl	ala	al	lā		lē	lā
	*lh₂									lā > lē
	*lh₃									lō
*l̥l	*l̥l	ir; ur	ar	ьl/ъl	il; ul	al, la				al	el	al
*r̥	*r̥	ṛ	ərə	rь/rъ	ir̃; ur̃	ar	ir, ri; ur, ru	är	ar, ur	ra	or	ri;ar	aúr	ur; or	yr
*r̥̄	*rh₁	īr; ūr	arə		ìr; ùr	ara	ra	rā		rē	rā
	*rh₂									rā > rē
	*rh₃									rō
*r̥r	*r̥r	ir; ur	ar	ьr/ъr	ir; ur	ar				ar	ar	ar
Trad. PIE	Laryng. PIE	Skr.	Av.	O.C.S.	Lith.	Arm.	Alb.	Toch.	Hitt.	Greek	Latin	Proto-Celtic	Gothic	normal	umlauted
Trad. PIE	Laryng. PIE	Skr.	Av.	O.C.S.	Lith.	Arm.	Alb.	Toch.	Hitt.	Greek	Latin	Proto-Celtic	Gothic	Old English

Notes:

^ Jump up to:^a ^b ^c ^d In initial syllables only.
^ Jump up to:^a ^b In non-final syllables only.
^ Jump up to:^a ^b Before i, ī, or /j/ in the next syllable in Proto-Germanic (i-umlaut).
^ In a closed syllable.
^ Jump up to:^a ^b ^c Before r, h. Gothic, but not other Germanic languages, merges /e/ and /i/.
^ Jump up to:^a ^b ^c ^d Before h, w, or before r, l plus a consonant (“breaking”).
^ Jump up to:^a ^b ^c ^d The existence of PIE non-allophonic a is disputed.
^ Before a back vowel in the next syllable (a restoration).
^ Jump up to:^a ^b ^c In open syllables (Brugmann’s law).
^ Jump up to:^a ^b ^c ^d Between consonants, or at the end of a word after a consonant.
^ Jump up to:^a ^b ^c At the beginning of a word, followed by a consonant.
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ In a final syllable.
^ Jump up to:^a ^b ^c ^d ^e ^f ā > ē in Attic and Ionic dialects only.
^ Before ā in the following syllable.
^ Jump up to:^a ^b ^c ^d ^e ^f The so-called breaking is disputed (typical examples are *proti-h₃kʷo- > Ved. prátīkam ~ Gk. πρόσωπον; *gʷih₃u̯o- > Ved. jīvá- ~ Arm. keank‘, Gk. ζωός; *duh₂ro- > Ved. dūrá- ~ Arm. erkar, Gk. δηρός)
^ Jump up to:^a ^b Under stress.
^ Before palatal consonants.
^ Before i in the following syllable.
^ Before wa.
^ Jump up to:^a ^b ^c Before a non-high vowel in the next syllable (a-mutation).
^ Before velars and unstressed
^ Jump up to:^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l In the neighbourhood of labiovelars.
^ Jump up to:^a ^b Before a stop or m.
^ Jump up to:^a ^b ^c ^d In the neighbourhood of labials.

Examples

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

*p

*pṓds, ~ *ped-, “foot”.

Vedic Sanskrit: pā́t, pád-
Avestan: paδa, pāδa
Old Church Slavonic: pěšĭ, “on foot”
Lithuanian: pėda, “foot bottom”
Armenian: otn
Tocharian: A pe, B pai
Luwian: pa-da-, pa-ta-
Ancient Greek: poús, podós
Latin: pēs, pedis
Celtiberian: ozas
Gothic: fotus (*p -> f by Grimm’s Law)

*t

*tréyes, “three”.

Vedic Sanskrit: tráyas
Avestan: θrāiiō
Old Church Slavonic: trĭje
Lithuanian: trỹs
Albanian: tre
Ancient Greek: treĩs
Latin: trēs
Old Irish: trí
Welsh: tri
Armenian: erekʿ
Gothic: þreis (*t -> þ by Grimm’s Law)

*ḱ

*ḱm̥tóm, “hundred” (from earlier *dk̂m̥tóm)

Vedic Sanskrit: śatám
Younger Avestan: satəm
Old Church Slavonic: sŭto
Lithuanian: šim̃tas
Tocharian: A känt, B känte
Ancient Greek: hekatón
Latin: centum (pronounced kentum)
Old Irish: cét
Welsh: cant
Gothic: hund (from proto-Germanic *xund-)

*k

*kréwh₂s, “raw flesh”

Vedic Sanskrit: kravís-, “raw meat”
Lithuanian: kraũjas, “blood”
Old Church Slavonic: kry, “blood”
Ancient Greek: kréas, “meat”
Latin: cruor, “raw blood”
Old Irish: crú, “blood, gore”
Old English: hrǣw, “raw”

Sound laws within PIE

A few phonological laws can be reconstructed that may have been effective prior to the final breakup of PIE by internal reconstruction.

Sievers’ law (Edgerton’s law, Lindeman’s option)
Bartholomae’s law
Szemerényi’s law
Stang’s law
Siebs’ law