pitch dark
Completely or extremely dark; having or allowing no or very little light. ("Pitch" is a viscous black resin produced from coal or wood tar.) The stars were covered by clouds, and there were no lights for miles, so it was pitch dark all around our campsite after we extinguished the fire. I hate going into the basement when it's pitch dark like that.
pitch dark
very dark; as dark as pitch. I couldn't see anything outside because it was pitch dark. The room was pitch dark, and I couldn't find the light switch!