Mizzenmast
Mizzenmast , noun
The definition varies slightly with the dictionary; in some dictionaries it is the last mast of a three-masted vessel; in others, it is the mast after the mainmast of a vessel of three or more masts. PJC.
(Nautical) the third mast from the bow in a vessel having three or more masts; the after and shorter mast of a yawl, ketch, or dandy.