The Merriam-Webster Word of the Day is crepuscular. Read on for what it means, how it’s used, and more.

What It Means

Crepuscular means “of, relating to, or resembling twilight.” It is also used in zoological contexts to describe creatures that are active during twilight, or to the activities of such creatures.

// As evening came on, fireflies began to appear in the crepuscular gloaming.

CREPUSCULAR in Context

“Cardinals, a crepuscular species, follow their own schedule, eating an early breakfast and a stylishly late dinner. They will break that schedule on very cold days.” — Jim Williams, The Star Tribune (Minneapolis, Minnesota), 16 Feb. 2022

Did You Know?

The early Romans had two words for the twilight. Crepusculum was favored by Roman writers for the half-light of evening, just after the sun sets; diluculum was reserved for morning twilight, just before the sun rises—it is related to lucidus, meaning “bright.” We didn’t embrace either of these Latin nouns as substitutes for our word twilight, but we did form the adjective crepuscular in the 17th century. The word’s zoological sense, relating to animals that are most active at twilight, developed in the 19th century.