A complete or (more often) partial absence of light.

(uncountable) Ignorance.

(uncountable) Nightfall.

A dark shade or dark passage in a painting, engraving, etc.

(intransitive) To grow or become dark, darken.

(intransitive) To remain in the dark, lurk, lie hidden or concealed.

(transitive) To make dark, darken; to obscure.

An adjective "dark" represents the state of having a lack of light, often referring to a source of light being extinguished, or being deprived of sight.

Transmitting, reflecting, or receiving inadequate light to render timely discernment or comprehension: caliginous, darkling, dim, gloomy, lightless, sombre.

(of colour) Dull or deeper in hue; not bright or light.

Ambiguously or unclearly expressed: enigmatic, esoteric, mysterious, obscure, undefined.

Marked by secrecy and hidden intentions, often used to describe clandestine activities or race horses with unknown racing capabilities.

Without moral or spiritual light; sinister, malign.

Conducive to hopelessness; depressing or bleak.

(of a time period) Lacking progress in science or the arts.

Extremely sad, depressing, or somber, typically due to, or marked by, a tragic or undesirable event.

With emphasis placed on the unpleasant aspects of life; said of a work of fiction, a work of nonfiction presented in narrative form, or a portion of either.

(broadcasting, of a television station) Off the air; not transmitting.