εἴκοσι (for εἴκοσιν v. infr.), Att., Ion., also Arc., IG5(2).3.1 (Tegea), and Aeol., ib.12(2).6.21 (Lesbos):— indecl.,
twenty
, Il.2.510,748, etc.; in Hom. more freq. in Ep. form ἐείκοσι, before a vowel ἐείκοσιν, 1.309, 6.217, al.; Dor. fίκατιLeg.Gort.4.13, etc.; fείκατιTab.Heracl.2.71; Lacon. βείκατιHsch.; εἴκατιIG9(1).693.10 (Corc.), Theoc.4.10, 5.86. (Orig. fῑ́κατι and ἐfῑ́κοσι, whence ἐείκοσι in Hom.; fείκατι and εἴκατι are late spellings of (f)ῑ́κατι; εἴκοσι is contr. from ἐfῑ́κοσι. Cf. Lat.
vīginti
, Skt.
viatis.
εἴκοσιν is the only form used by Ar., whether before vowels or consonants (εἴκοσ' ἀπολογίζεται is dub. in Fr.465); also (before consonants) Herod.3.91, Phld.Piet.3, etc., but not common in Inscrr. or Pap., e.g. (before consonants) Schwyzer707 B2 (Ephesus, vi B. C.), IG2.804.155 (iv B.C.), (before a vowel) PGrenf.2.75.7 (iv A. D.); εἴκοσι ἔτη, εἴκοσι ἡμερῶν, IG12.94,49.)