Szemerényi's law

Overview

The rule deleted coda fricatives *s or laryngeals *h₁, *h₂ or *h₃ (cover symbol *H), with compensatory lengthening occurring in a word-final position. In other words:

*/-VRs/, */-VRH/ > *-VːR */-VRH-/ > *-VR- (no examples of s-deletion can be reconstructed for PIE)

Morphological effects

The law affected the nominative singular forms of the many masculine and feminine nouns whose stem ended in a resonant:

PIE */ph₂térs/ "father" > *ph₂tḗr (Ancient Greek patḗr, Sanskrit pitā́)

PIE */ǵénh₁tors/ "parent" > *ǵénh₁tōr (Ancient Greek genétōr, Latin genitor)

PIE */dʰéǵʰoms/ "earth" > *dʰéǵʰōm (Ancient Greek khthṓn, Sanskrit kṣa, Hittite te-e-kán)

The rule also affected the nominative-accusative forms of neuter plural/collective nouns, which ended in *-h₂:

PIE */ǵénh₁monh₂/ "seeds" > */ǵénh₁mōn/ > *ǵénh₁mō (on n-deletion see below)

Also in the third-person plural perfect ending:

PIE */-ers/ (the third-person plural perfect ending) > *-ēr (Latin ēr-e, Hittite -er, -ir)

Compare:

PIE */werh₁-dʰh₁-o-/ "word" > *werdʰh₁o- (Latin verbum)

Further effects

According to another synchronic PIE phonological rule, word-final *n was deleted after *ō, usually by the operation of Szemerényi's law:

PIE */ḱwóns/ "dog" > */ḱwṓn/ > *ḱwṓ (Sanskrit ś(u)vā́, Old Irish cú)

The PIE reconstruction for "heart" is the single instance where *d is deleted after *r, with compensatory lengthening of the preceding vowel. It is not clear whether that is an isolated example or a part of a broader process such as Szemerényi's law.

PIE */ḱérd/ "heart" > *ḱḗr (Ancient Greek kêr, Hittite ker)

Exceptions

Some cases were apparently not affected by Szemerényi's law:

The accusative plural *-ons of thematic nominals.

The genitive singular of stems ending in sonorants, such as *déms "of the house" (fossilised in the phrase *dems potis "master of the house").

Secondary 2nd person singular verb ending *-s with verbs ending in sonorants, such as *gʷéms (from the root *gʷem- "to step, to come").

Morphologization

In PIE, the resulting long vowels had already begun to spread analogically to other nominative singular forms that were not phonologically justified by the law (PIE *pṓds 'foot'). The word-final sonorants other than *-n were sometimes dropped as well, which demonstrates that this law was already morphologized in the period of "PIE proper", and the long vowel produced was no longer synchronically viewed as the outcome of a process of fricative deletion. Exceptions to Szemerényi's law are found in word-final:

PIE */gʷénh₂s/ "woman" > *gʷḗn (Old Irish bé) but also *gʷénh₂ (Sanskrit jáni)

PIE *wih₁roms "men" (and not **wih₁rōm) > Gothic wairans

PIE *sals "salt" (and not **sāl) > Ancient Greek háls

as well as medial positions:

PIE *gen- > Sanskrit janman, PIE *genh₁- > Sanskrit jánitrī

The forms without a laryngeal are considered to be more archaic and were likely to have been lexicalized at a later stage of PIE.