Strong G6586ἀτάρ

1. but, yet , Lat. at, to introduce an objection or correction, (Iliad by Homer), attic; it always begins a sentence or clause, but is placed after the vocative, Ἕκτορ, ἀτάρ που ἔφης still thou didst say, (Iliad by Homer):—; ἀτάρ sometimes answers to μέν, more emphatic than δέ, (Homer), attic
2. in attic to mark a rapid transition to another thought, (Aeschulus Tragicus), etc.; so ἀτὰρ δή (Euripides) (ML)