with little or no light

it's too dark to see much

a dark alley

you'd better set off before it gets dark

(of a colour or object) not reflecting much light; approaching black in shade

dark green

(of a period or situation) characterized by great unhappiness or unpleasantness

the dark days of the war

she took to Instagram to share a story about a dark time in her life

this house has a dark past

hidden from knowledge; mysterious

a dark secret

denoting a velarized form of the sound of the letter l as it sounds at the end of a word or before another consonant (as in full or bulk in most accents of English)

the absence of light in a place

Carolyn was sitting in the dark

a dark colour or shade, especially in a painting

lights and darks are juxtaposed arbitrarily to create a sense of shallow relief