What does "mast" mean?

Mast: (Naut.) A pole, or long, strong, round piece of timber, or spar, set upright in a boat or vessel, to sustain the sails, yards, rigging, etc. A mast may also consist of several pieces of timber united by iron bands, or of a hollow pillar of iron or steel. The tallest pine Hewn on Norwegian hills, to be the mast Of some great ammiral. Milton. Note: The most common general names of masts are foremast, mainmast, and mizzenmast, each of which may be made of separate spars.

Additional senses

  1. 2.(Mach.) The vertical post of a derrick or crane. Afore the mast, Before the mast. See under Afore, and Before. -- Mast coat. See under Coat. -- Mast hoop, one of a number of hoops attached to the fore edge of a boom sail, which slip on the mast as the sail is raised or lowered; also, one of the iron hoops used in making a made mast. See Made.
  2. 3.To furnish with a mast or masts; to put the masts of in position; as, to mast a ship.

Sources