Source : Webster's Revised Unabridged Dictionary (1913)

Headfish \Head`fish"\, n. (Zo["o]l.)
   The sunfish ({Mola}).

Source : WordNet®

headfish
     n : among the largest bony fish; pelagic fish having an oval
         compressed body with high dorsal and anal fins and caudal
         fin reduced to a rudder-like lobe; worldwide in warm
         waters [syn: {ocean sunfish}, {sunfish}, {mola}]