πηγαῖον ῥέος

From LSJ

οἵτινες πόλιν μίαν λαβόντες εὐρυπρωκτότεροι πολύ τῆς πόλεος ἀπεχώρησαν ἧς εἷλον τότεafter taking a single city they returned home, with arses much wider than the city they captured

Source

Greek > English (Woodhouse)

gushing stream