ἦμος · ēmos — LSJ
at which time, when, in Hom., freq. in protasi with τῆμος, τῆμος ἄρα . . , τῆμος δή . . , etc., in apodosi (v. τῆμος) ; ἆμος . . , τᾶμος . . Theoc. 13.25; ἦ. . . , δὴ τότε Il. 1.475, al.: folld. by δὴ τότʼ ἔπειτα Od. 17.1; by καὶ τότε δή Il. 8.68; by καὶ τότʼ ἔπειτα 1.477; by καὶ τότε δή ῥα 16.779; by ἄρα or ῥά alone, Od. 2.1, 19.428, cf. S. Aj. 935 (lyr.); by τηνικαῦτα Hdt. 4.28; by τότε S. Tr. 155: rarely without some particle in apodosi, as Od. 3.491, E. Hec. 915 (lyr.); ἦ. ὅτε A.R. 4.267, 45
with pres., while, so long as, S. Tr. 531: or impf., Id. OT 1134.