The headword is a neuter noun (see LSJ s.v. mo/sxeuma) in the nominative/vocative/accusative plural. If it has been directly quoted from somewhere, the possibilities include Theophrastus, On the Causes of Plants 3.11.5, where it is used to describe the preferred type of well-rooted offsets for propagating trees in wet regions. But more probably, as noted by Adler (and cf. Latte on Hesychius mu1709 s.v.), it was generated by the genitive plural in Wisdom of Solomon 4.3 LXX.
[1] The headword is identically glossed in Photius' Lexicon (mu546 Theodoridis), Synagoge mu272, and Lexica Segueriana 303.24; cf. Bekker 280.18, and cognates at mu 1274, mu 1275, mu 1276, and mu 1277.