Pitch-black describes complete darkness where you can't see anything at all, not even your hand held right in front of your face. When a room is pitch-black, there's no light coming from windows, no glow from electronic devices, absolutely nothing to help your eyes adjust.

Pitch is a thick, black tar-like substance once used to waterproof ships. It is so dark that it became a measure for total darkness. A cave deep underground with no flashlight is pitch-black. A forest at night with clouds covering the moon might be pitch-black. If you've ever woken up in the middle of the night in a room with blackout curtains and no nightlight, you know what pitch-black feels like: it's disorienting because your eyes search for any hint of light but find nothing.

People also use pitch-black to describe things that are simply extremely dark in color, like pitch-black hair or a pitch-black cat. But the strongest meaning describes that unsettling moment when darkness is so complete that you lose your usual confidence about where things are.