The headword is a masculine noun in the accusative plural; see generally LSJ s.v. o(lko/s, and cf. omicron 175, and omicron 176. (An adjectival form exists as well: o(lko/s, -h/, -o/n, drawing to oneself, attractive; cf. omicron 177, omicron 178, and omicron 179.)
[In her critical apparatus Adler notes that this entry (together with omicron 179) was omitted by ms F.]
[1] The gloss is the same form as the lemma; see generally LSJ s.v. nau/staqmos, o( (and nu 78). The headword is identically glossed in Hesychius omicron590, the Synagoge, Photius' Lexicon (omicron233 Theodoridis), and Lexica Segueriana 316.26. The entry is taken to be generated by Euripides, Rhesus 673 (web address 1): Athena, disguised as Aphrodite to trick Paris into leaving, calls out to warn Odysseus and Diomedes [Author, Myth] of approaching Trojans and urges them to escape back pro\s o(lkou\s nausta/qmwn (the logical place to establish a defensive perimeter).