n. A stick, staff, pole, rod, beam, or other rigid thing used to sustain an incumbent weight; that on which anything rests for support; a support; a stay; a fulcrum: usually applied to something not forming a part of the object supported: as, a prop for vines; a prop for an old wall.n. In botany, same as fulcrum, 3.n. plural Legs.n. Synonyms See staff.To support or prevent from falling by placing something under or against: as, to prop a roof or wall.To support by standing under or against: as, a pillar props a roof; beams prop a wall.To support or sustain in a general sense: as, to prop a failing cause.To help; assist.To stop or pull up suddenly; balk: said of a horse or other beast.n. A shell used in the game of props. See props.n. An abbreviation of proposition; properly.n. An unexpected stop, as of a horse.