Definition of pitch-darkness:
(n) :
A sticky, gummy substance secreted by trees; sap.
(n) :
A dark, extremely viscous material still remaining after distilling crude oil and tar.
(n) :
(geology) Pitchstone.
(v) :
To cover or smear with pitch.
(v) :
To darken; to blacken; to obscure.
(adj) :
Very dark black; pitch-black.