No equivalent entry in other lexica.
The headword is a feminine noun in the nominative (and vocative) singular; see generally LSJ s.v. It might be extracted from [Aristotle], On Colors 3 (793a12-13) (or subsequent commentary), where both the headword and gloss appear (see next note); but the word is not uncommon in philosophical contexts. (Another possibility [DW] is technical military literature: see LSJ s.v. I.6, citing Aelian Tacticus and Arrian.)
cf. generally sigma 1523, sigma 1525, sigma 1526, sigma 1527; also epsilon 636 (where the present headword is the gloss).
[1] The gloss is the same form as the headword. The entry might be generated from the aforementioned passage in [Aristotle], which notes that "lustre is nothing other than the continuity and density of light"; see Barnes, p. 1221.