Pertaining to twilight; glimmering; hence, imperfectly clear or luminous. "This semihistorical and crepuscular period."
2.
(Zool.) 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."
... "one hesitates to mention it to so excellent a custodian of the family reputation—still there are other things to me somewhat—somewhat crepuscular." ... — Doom Castle • Neil Munro Read full book for free!