To lift or raise by pushing from behind, as a person climbing a tree; push up: often used figuratively: as, to boost a person over a fence, or into power.n. An upward shove or push; the act of boosting; the result of boosting; a lift, either literally or figuratively: as, to give one a boost.n. A Middle English form of boast.n. Same as boist.Same as buist.