ψίλαξ
From LSJ
γραμματική ἐστιν ἐμπειρία τῶν παρὰ ποιηταῖς τε καὶ συγγραφεῦσιν ὡς ἐπὶ τὸ πολὺ λεγομένων → grammar is a practical knowledge of the usage of poets and writers of prose
English (LSJ)
(A) [ῑ], ακος, ὁ,
A = ψιλός, Ar.Fr.891.
ψίλαξ (B), ακος, ὁ, epith. of Dionysus at Amyclae, Paus.3.19.6; he explains it as
A winged (from ψίλον Dor. for πτίλον), which suggests that it has ῐ.