The Collaborative International Dictionary of English v.0.48:

Boost \Boost\ (b[=oo]st), v. t. [imp. & p. p. Boosted; p. pr.
   & vb. n. Boosting.] [Cf. Boast, v. i.]
   To lift or push from behind (one who is endeavoring to
   climb); to push up; hence, to assist in overcoming obstacles,
   or in making advancement. [Colloq. U. S.]
   [1913 Webster]