Source : Webster's Revised Unabridged Dictionary (1913)

Mizzen \Miz"zen\, a. [It. mezzana, fr. mezzano middle, fr. mezzo
   middle, half: cf. F. misaine foresail. See {Mezzo}.] (Naut.)
   Hindmost; nearest the stern; as, the mizzen shrouds, sails,
   etc.

Mizzen \Miz"zen\, n. (Naut.)
   The hindmost of the fore and aft sails of a three-masted
   vessel; also, the spanker.

Source : WordNet®

mizzen
     n 1: third mast from the bow in a vessel having three or more
          masts; the after and shorter mast of a yawl, ketch, or
          dandy [syn: {mizzenmast}, {mizenmast}, {mizen}]
     2: fore-and-aft sail set on the mizzenmast [syn: {mizen}]