that which flows, a river, stream, ποταμοῖο ῥέεθρα the streams, waters of . ., Il. 14.245; ἐρατεινὰ ῥ. 21.218; Στυγὸς ὕδατος αἰπὰ ῥ. 8.369, cf. h.Hom. 19.9, etc.; παρθενόσφαγα ῥ. streams of a maidenʼs blood, A. Ag. 210 (lyr.): sg., ἐκτρέψασα τοῦ ποταμοῦ τὸ ῥέεθρον πᾶν ἐς τὸ ὤρυξε χωρίον Hdt. 1.186, cf. 179, Th. 7.74; Ἀλφεοῦ ῥέεθρον Pi. O. 9.18; ῥέεθρον ἁγνοῦ Στρυμόνος A. Pers. 497; ὅταν περάσῃς ῥεῖθρον Id. Pr. 790; esp. of rivulets, brooks, X. Cyn. 5.15, Plb. 3.71.4, Jul. Or. 3.126d.