Georg Autenrieth, A Homeric Dictionary

ἀτάρ (ἀτα?ρ, ε 108, Od. 19.273): but yet, but, however; freq. corresponding to μέν in the previous clause, Il. 1.166, Il. 6.86, 125; to ἦ μήν, Il. 9.58; but often without preceding particle, and sometimes with no greater adversative force than δέ, e. g. μάψ, ἀτὰρ οὐ κατὰ κόσμον, i. e. οὐδὲ κατὰ κ., Il. 2.214, Od. 3.138; in apod., like δέ, Il. 12.144. ἀτάρ is always the first word in the clause, but a voc. is not counted, Ἕκτορ, ἀτὰρ σύ μοί ἐσσι πατὴρ καὶ πότνια μήτηρ, ‘but thou, Hector.’ With this arrangement there is nothing peculiar in the force of the particle; it refers here, as always, to what precedes (expressed or implied) even when the voc. introduces the whole passage, Ἕκτορ, ἀτάρ που ἔφης, ‘doubtless thou didst think,’ etc., Il. 22.331, cf. Od. 4.236. (Weakened form of αὐτάρ).