{ Cre*pus"cu*lar (-k?-l?r), Cre*pus"cu*lous (-l?s), } a. [Cf. F. crépusculaire.] 1. Pertaining to twilight; glimmering; hence, imperfectly clear or luminous.

This semihistorical and crepuscular period.
Sir G. C. Lewis.

2. (Zoöl.) Flying in the twilight or evening, or before sunrise; -- said certain birds and insects.

Others feed only in the twilight, as bats and owls, and are called crepuscular.
Whewell.