dark

Having an absolute or (more often) relative lack of light.

“The room was too dark for reading.”

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

“my sister's hair is darker than mine;  her skin grew dark with a suntan”

Hidden, secret, obscure.

Without moral or spiritual light; sinister, malign.

“a dark villain;  a dark deed”

Conducive to hopelessness; depressing or bleak.

“the Great Depression was a dark time;  the film was a dark psychological thriller”

Lacking progress in science or the arts; said of a time period.

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.

“The ending of this book is rather dark.”

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

“Dark surrounds us completely.”

Ignorance.

“The lawyer was left in the dark as to why the jury was dismissed.”

Nightfall.

“It was after dark before we got to playing baseball.”

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

To grow or become dark, darken.

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

To make dark, darken; to obscure.