Source : Webster's Revised Unabridged Dictionary (1913)

Fathead \Fat"head`\, n. (Zo["o]l.)
      (a) A cyprinoid fish of the Mississippi valley
          ({Pimephales promelas}); -- called also {black-headed
          minnow}.
      (b) A labroid food fish of California; the redfish.

Source : WordNet®

fathead
     n : a man who is a stupid incompetent fool [syn: {goof}, {goofball},
          {bozo}, {jackass}, {goose}, {cuckoo}, {twat}, {zany}]