Amphikinetic

The Proto-Indo-European word for ‘lake’ was amphikinetic: nominative singular *léy-mon-s, genitive *li-mn-és.

Amphikinetic ('both ends mobile'): the accent moves between the first syllable (root) and the case-markers.

The other three polysyllabic types exhibited alternating accent: on the leftmost syllable of the stem in the direct cases and on the endings in the oblique cases ('amphikinetic' accent); on the rightmost syllable of the stem in the direct cases and on the endings in the oblique cases ('hysterokinetic' accent); or on the penultimate syllable of the stem in the direct cases and on the rightmost syllable of the stem in the oblique cases ('proterokinetic' accent). Note that in every one of these patterns the accent was to the left in the direct cases and to the right in the oblique cases. The amphikinetic type appears to be the most archaic; isolated examples survive only in Hittite and the Indo-Iranian languages. Securely reconstructable amphikinetic nouns include, for instance, (masc.) *póntoh₂- ~ *pn̥th₂-´ 'path', *léymon- ~ *limn-´ 'lake', (fem.) *dʰéǵʰōm ~ *ǵʰm-´ (loc. *ǵʰdʰsém) 'earth', and neuter collectives such as *wédōr ~ *udn-´ 'waters' (cf. Schindler 1975a: 3-4). Interestingly, the inflection of masculine n-stems in Germanic appears to have evolved from an originally amphikinetic pattern (cf. Jasanoff 2002: 32-5), which suggests that this type of inflection had not yet been reduced to relics in late PIE.

In amphikinetic (or holokinetic) nouns, the root is accented in the strong cases, the ending in the weak, and the suffix is typically in the lengthened o-grade (rather than the expected zero-grade) in the nominative singular and ordinary o-grade in the accusative singular. The word for 'dawn' belongs here, nomin. sing. *h₂éus-ōs (Aeolic Gk. aúōs, Lat. aurōr-a), accus. sing. *h₂éus-os-m̥ (Ved. uṣā́sam, remade with zero-grade of the root), genit. sing. *h₂us-s-és (Ved. uṣás). Another famous example is the word for 'earth', nomin. *dʰéĝʰōm (Hitt. tēkan), accus. *dʰéĝʰom-m (> *dʰéĝʰōm by Stang's Law, §3.38, to become ultimately Ved. kṣā́m), genit. *dʰĝʰm-és (Hitt. taknāš, Ved. jmás). Yet another famous amphikinetic noun is the word for 'path', which will be discussed in §11.25.