The headword, evidently quoted from somewhere (perhaps Cyril of Alexandria, who uses it in similes: De adoratione et cultu in spiritu et veritate 9 (PG 68,612b) or Glaphyra in Pentateuchum 2 (PG 69,68c), is a neuter noun in the nominative/vocative/accusative plural. There is an alternative accentuation on the penult, mosxi/a; see LSJ Supplement (1968) s.v. mosxi/on, Lexica Segueriana 303.26, and Synagoge mu274.
[1] The headword is identically glossed in the Synagoge, Hesychius mu1711, and Photius' Lexicon (mu548 Theodoridis); cf. cognates at mu 1273, mu 1274, mu 1276, and mu 1277.