Source : Webster's Revised Unabridged Dictionary (1913)

Leatherneck \Leath"er*neck`\, n. (Zo["o]l.)
   The sordid friar bird of Australia ({Tropidorhynchus
   sordidus}).

Source : WordNet®

leatherneck
     n : a member of the United States Marine Corps [syn: {Marine}, {devil
         dog}, {shipboard soldier}]