Source : Webster's Revised Unabridged Dictionary (1913)

Sperm \Sperm\, n.[Contr. fr. spermaceti.]
   Spermaceti.

   {Sperm oil}, a fatty oil found as a liquid, with spermaceti,
      in the head cavities of the sperm whale.

   {Sperm whale}. (Zo["o]l.) See in the Vocabulary.

Source : WordNet®

sperm oil
     n : an animal oil found in the blubber of the sperm whale