Source : Webster's Revised Unabridged Dictionary (1913)

Spermaceti \Sper`ma*ce"ti\, n. [L. sperma sperm + cetus,gen.
   ceti, any large sea animal, a whale, Gr. ???. See {Sperm},
   {Cetaceous}.]
   A white waxy substance obtained from cavities in the head of
   the sperm whale, and used making candles, oilments,
   cosmetics, etc. It consists essentially of ethereal salts of
   palmitic acid with ethal and other hydrocarbon bases. The
   substance of spermaceti after the removal of certain
   impurities is sometimes called cetin.

   {Spermaceti whale} (Zo["o]l.), the sperm whale.

Source : WordNet®

spermaceti
     n : a white waxy substance from oil of the sperm whale