ξεῖ
ξεῖ, τό, indecl., name of the letter ξ, Calliasap. , 10.453d BCH 29.483 (Delos), P 0.2.3 : later
A). ξῖ Jud.Voc. 9 , Sch.D.T. p.489 H., etc.; ξῦ (by assimilation to νῦ), f.l. in l. c. and AP 9.385.14 ( Gramm.).