figurative use from 1660s; literal use from 1755, from Latin crepusculum "twilight, dusk," from creper "dusky," which is of unknown origin. Especially of evening twilight.

a term describing animals active during dawn and dusk. Read more on: Crepuscular

Daily cycles with peak activity around dusk and/or dawn. cretin

Active at dawn and dusk.

(L: crepusculum= twilight; of twilight) descriptive term for an animal which is active in the twilight but sleeps during the middle of the day and night.

(adj) like twilight; dim

Appearing or active at twilight.

active at dawn and dusk

Active mainly at dawn and dusk.

refers to animals that are primarily active during twilight hours including both dusk and dawn crop :: an expanded muscular pouch near the throat where food is temporaily stored and then digested

Active primarily in dim light, around the hours of dawn and dusk.

Becomes active at dusk, dawn, and twilight.

Most active at dawn and twilight. Culling:

Animals that become active at dusk, dawn or twilight.

having activity periods during low light levels at dawn and evening

Times in the morning and evening when it is between daylight and dark. Crepuscular times are when some animal species are most active, including Eastern Gray Squirrels and White-tailed Deer.

  Times in the morning and evening when it is between daylight and dark. Crepuscular times are when some animal species are most active. Stag beetles, most moths and bats are often seen in the evening [..]

 with activity periods at dusk and/or dawn. Many frequently-seen moths, such as the White-lined Sphinx Moth (Hyles lineata), are crepuscular.

active at dawn and/or at dusk

The habit of becoming active in the half light of dusk or dawn, and being quiescent during bright daylight and total darkness.

animals that are active in the twilight; i.e., at pre-dawn and at dusk

Active at dawn, dusk or in deeply shaded conditions.

A term used to describe some animals that are primarily active during twilight, that is at dawn and at dusk.