The headword is the nominative/ accusative plural -- glossed here as nominative -- of the noun e)/palcis. This form of the noun occurs numerous times in Homer's Iliad, e.g. 12.258 (web address 1), and this first part of the entry perhaps derives from the scholia vetera to dative plural e)pa/lcesin in Iliad 22.3 (e)pa/lceis ga\r oi( tw=n teixw=n lego/menoi promaxw=nes). The word also occurs frequently in prose, e.g. Thucydides 3.21.3 (web address 2).
See also epsilon 1947, mu 1272, pi 2501, pi 3201.
[1] Up to this point the entry = Lexica Segueriana 226.9; cf. Hesychius epsilon4144 (and Etymologicum Magnum 353.20).
[2] Greek Anthology 5.294.3 (Agathias Scholasticus). Here the word occurs in the nominative singular.