Dark

adjective

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

   "The room was too dark for reading."

2. (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"

3. Hidden, secret, obscure.
4. Without moral or spiritual light; sinister, malign.

   "a dark villain;  a dark deed"

5. Conducive to hopelessness; depressing or bleak.

   "the Great Depression was a dark time;  the film was a dark psychological thriller"