Source : Webster's Revised Unabridged Dictionary (1913)

Pitch-dark \Pitch"-dark`\, a.
   Dark as a pitch; pitch-black.

Source : WordNet®

pitch-dark
     adj : extremely dark; "a black moonless night"; "through the
           pitch-black woods"; "it was pitch-dark in the celler"
           [syn: {black}, {pitch-black}]