Real Dictionary

mast in American English 1
a tall spar or, now often, a hollow metal structure, sometimes in sections, rising vertically from the keel or deck of a vessel and used to support the sails, yards, radar and radio equipment, etc.
noun: a spar or structure rising above the hull and upper portions of a ship or boat to hold sails, spars, rigging, booms, signals, etc., at some point on the fore-and-aft line, as a foremast or mainmast

mast in American English 2
beechnuts, acorns, chestnuts, etc., esp. as food for hogs
noun: the fruit of the oak and beech or other forest trees, used as food for hogs and other animals

mast in British English 1
noun: any vertical spar for supporting sails, rigging, flags, etc, above the deck of a vessel or any components of such a composite spar

mast in British English 2
noun: the fruit of forest trees, such as beech, oak, etc, used as food for pigs

mast- in American English
masto-
combining form

mast- in British English
combining form