The headword, evidently extracted from somewhere, is a masculine noun in the nominative (and vocative) plural; see LSJ s.v. o)/xqos, and cf. omicron 1050 (and more generally chi 592).
[1] The glossing nouns are feminine nominative plural forms; see LSJ s.v. pe/tra (rock, cliff, ledge) and s.v. e)coxh/ (prominence, elevated feature). The headword is identically glossed in the Synagoge, Photius' Lexicon (omicron742 Theodoridis), and Lexica Segueriana 323.24; cf. Hesychius omicron2032 and ps.-Zonaras 1492.6.