The Collaborative International Dictionary of English v.0.48:
bonnet head \bonnet head\, bonnethead \bonnethead\n. (Zool.), small harmless hammerhead shark (Sphyrna tiburio) of the southern United States and West Indies, having a spade-shaped head; abundant in bays and estuaries. Syn: shovelhead, bonnet shark, Sphyrna tiburo. [1913 Webster + WordNet 1.5]