Herbert Weir Smyth, A Greek Grammar for Colleges

ACCUSATIVE SINGULAR

γῦπ-α, ὄνυχ-α, ἐλέφαντ-α, λιμέν-α, ῥήτορ-α, λέοντ-α; πόλι-ν, ἰχθύ_-ν, βοῦ-ν from πόλι-ς city, ἰχθύ_-ς fish, βοῦ-ς ox, cow. Stems in ευ take α (275).

[*] 247. Barytone stems of two syllables ending in ιτ, ιδ, ι_θ usually drop the dental and add ν.

χάρις grace (stem χαριτ-) χάριν, ἔρις strife (ἐριδ-) ἔριν, ὄρνι_ς bird (ὀρνι_θ-) ὄρνι_ν. So εὔελπις hopeful (εὐελπιδ-) εὔελπιν (292). Oxytones end in α: ἐλπίδ-α, σφρα_γῖδα (σφρα_γί_ς seal).

a. κλεῖς key (κλειδ-), Old Att. κλῄς, has κλεῖν (late κλεῖδα), acc. pl. κλεῖς (late κλεῖδας).

[*] 247 D. The acc. in α (χάριτα, ἔριδα, ὄρνι_θα) occurs in Hom., Hdt., and in Attic poetry. So κόρυθα and κόρυν (κόρυς helmet) in Hom.