noun

• (nautical, communication, aviation) A tall, slim post or tower, usually tapering upward, used to support, for example, sails or observation platforms on a ship, the main rotor of a helicopter, flags, floodlights, meteorological instruments, or communications equipment, such as an aerial, usually supported by guy-wires (except in the case of a helicopter).
• (naval) A non-judicial punishment ("NJP"); a disciplinary hearing under which a commanding officer studies and disposes of cases involving those under his command.

verb

• (of swine and other animals) To feed on forest seed or fruit.
• (agriculture, forestry, ecology, of a population of plants) To produce a very large quantity of fruit or seed in certain years but not others.
  "Any individual tree which masted in a generally non-mast year would be subjected to the exclusive attention of the seed predators and so would be selected against."

noun

• (bodybuilding slang) The anabolic steroid drostanolone propionate, also known as Masteron

noun

• (obsolete, billiards) A type of heavy cue, with the broad end of which one strikes the ball.
  "Godfrey thus conquered, pretended to lose his temper, curs'd his own ill luck, swore that the table had a cast, and that the balls did not run true, changed his mast, and with great warmth challenged his enemy to double his sum."