[1] Likewise or similarly in other lexica; references at Photius upsilon166 Theodoridis. The headword -- third person singular, present indicative, of the epic/Ionic verb u(pi/sxomai, glossed with the equivalent Attic form -- is probably quoted from Homer, Iliad 23.209 (web address 1), but see also Odyssey 2.91 = 13.380; cf. pi 2702. For the verb, see also upsilon 400.
[2] Aorist participle, masculine nominative singular, of the same verb. The form occurs three times in Homer (and twice in the plural).