For this equivalence see already tau 781. If this aorist active participle of u(potope/w is quoted from somewhere in this precise form, masculine nominative singular, the source is perhaps Thucydides 2.13.1; note, however, the corresponding plural in Thucydides 1.20.2, glossed thus in the scholia there.
Likewise or similarly in other lexica; references at Photius upsilon263 Theodoridis.