Dark
Part of speech: noun
Definition: A complete or (more often) partial absence of light. Ignorance. Nightfall.
Part of speech: adjective
Definition: Having an absolute or (more often) relative lack of light. Dull or deeper in hue; not bright or light. Hidden, secret Without moral or spiritual light; sinister, malign. Conducive to hopelessness; depressing or bleak 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
Example sentence: I'm so fast that last night I turned off the light switch in my hotel room and was in bed before the room was dark.
Concealed
Part of speech: verb
Definition: To hide something from view or from public knowledge, to try to keep something secret.
Example sentence: Seek not to know what must not be reveal, for joy only flows where fate is most concealed. A busy person would find their sorrows much more; if future fortunes were known before!