A.the time just before or about daybreak, dawn, cock-crow (“ἀπ᾽ ὄρθρου μέχρι περ ἂν ἥλιος ἀνάσχῃ” Pl.Lg.951d), “τάχα δ᾽ ὄ. ἐγίγνετο δημιοεργός” h.Merc.98 ; “ἐπειδὰν ὄ. ᾖ” Ar.Ach.256, cf. Av.496, etc. ; “ὄρθρου” at dawn, Hes.Op.577, Sopat.25, Aristopho 10 ; “ὄρθρου γενομένου” Hdt.1.198 ; “ἅμα ὄρθρῳ” Id.7.188, Th.3.112, etc. ; “ἐς ὄρθρον” Theoc.18.56, cf. X.Cyn.6.6 ; “κατ᾽ ὄρθρον” Ar.V.772 ; “περὶ ὄρθρον” Th.6.101 (cf. περίορθρος) ; πρὸς ὄρθρον towards dawn, Ar.Lys.1089 ; “πρὸς ὄρθρον γ᾽ ἐστίν” Id.Ec.20 ; “ὑπ᾽ ὄρθρον” Batr.103 ; “ὑπὸ τὸν ὄ.” D.C.76.17 ; τὸν ὄ., abs., in the morning, Hdt.4.181 ; δι᾽ ὄρθρων each morning early, E.El. 909 ; ὄ. βαθύς dim morning twilight, “ἀλλὰ νῦν ὄ. β.” Ar.V.216, cf. Pl. Cri.43a, Theoc.18.14 ; “τῆς παρελθούσης νυκτὸς . . , ἔτι βαθέος ὄ.” Pl.Prt. 310a, cf. Ev.Luc.24.1.
II. Ὄρθρος , ὁ, a mythical dog, son of Typhaon and Echidna, that kept the herds of Geryoneus on the island Erytheia, and was there killed by Heracles, Hes.Th.309, cf. 293 (v.l. Ὄρθος).
