Lucifugous is a rarely used adjective that means tending to avoid light or sunlight. Synonyms for lucifugous include crepuscular, shady, shadowy, dim, dark, dusky, obscure, and tenebrous. Crepuscular specifically refers to animals that are active during twilight hours, while shady and shadowy generally describe places that are covered or shielded from sunlight. Dim, dark, dusky, obscure, and tenebrous all suggest low light levels or a lack of brightness. These words can be used interchangeably with lucifugous to describe organisms, environments, or behaviors that are associated with dim light or darkness.