Used other than figuratively or idiomatically: Without light; somewhere that is dark.
I tripped over his suitcase in the dark.
(idiomatic) Without information.
Management kept the board of directors completely in the dark.
I was in the dark about the surprise party until I walked in.
They remained in the dark until the newspaper story came out.
(poker slang) Without looking at one's hole cards, thus not knowing what they are.
Source: en.wiktionary.orgConfession is like a bridle that keeps the soul which reflects on it from committing sin, but anything left unconfessed we continue to do without fear as if in the dark. John Climacus
An audience is never wrong. An individual member of it may be an imbecile, but a thousand imbeciles together in the dark - that is critical genius. Billy Wilder
Walking with a friend in the dark is better than walking alone in the light. Helen Keller
All cats are gray in the dark. Vietnamese Proverb
Gypsy gold does not chink and glitter, it gleams in the sun and neighs in the dark. Gypsy Proverb
All cats are grey in the dark. English Proverb