Definition of mast
1
: a long pole or spar rising from the keel or deck of a ship and supporting the yards, booms, and rigging
2
: a slender vertical or nearly vertical structure (such as an upright post in various cranes)
3
: a disciplinary proceeding at which the commanding officer of a naval unit hears and disposes of cases against enlisted men — called also
captain's mast
—
before the mast
1
: forward of the foremast
2
: as a common sailor
