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]

The Collaborative International Dictionary of English v.0.48:

Boost \Boost\ (b[=oo]st), n.
   A push from behind, as to one who is endeavoring to climb;
   help. [Colloq. U. S.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

boost
    n 1: the act of giving hope or support to someone [syn: boost,
         encouragement]
    2: an increase in cost; "they asked for a 10% rise in rates"
       [syn: rise, boost, hike, cost increase]
    3: the act of giving a push; "he gave her a boost over the
       fence"
    v 1: increase; "The landlord hiked up the rents" [syn: hike,
         hike up, boost]
    2: give a boost to; be beneficial to; "The tax cut will boost
       the economy"
    3: contribute to the progress or growth of; "I am promoting the
       use of computers in the classroom" [syn: promote,
       advance, boost, further, encourage]
    4: increase or raise; "boost the voltage in an electrical
       circuit" [syn: boost, advance, supercharge]
    5: push or shove upward, as if from below or behind; "The singer
       had to be boosted onto the stage by a special contraption"

Moby Thesaurus II by Grady Ward, 1.0:

340 Moby Thesaurus words for "boost":
   Great Leap Forward, a leg up, abstract, access, accession,
   accretion, accrual, accruement, acculturate, accumulation,
   acknowledgment, add to, addition, advance, advancement, advantage,
   advertise, advocate, aggrandize, aggrandizement, aid, ameliorate,
   amelioration, amend, amendment, amplification, amplify, and,
   animate, annex, appreciation, appropriate, ascent, assault, assist,
   assistance, augment, augmentation, back, bag, ballooning, ballyhoo,
   bark, bear, bear upon, bearing, beef up, better, bettering,
   betterment, bill, bloating, blurb, boom, borrow, breakthrough,
   brighten, bring forward, broaden, broadening, buck, build,
   build up, buildup, bull, bulldoze, bulletin, bump, bump against,
   bunt, buoy up, butt, butt against, cast up, cheer, circularize,
   civilize, commend, commendation, conduce to, contribute to, cop,
   cram, crescendo, crib, crowd, cry up, defraud, development, dig,
   drive, edema, edify, educate, elbow, elevate, elevation, embezzle,
   emend, encourage, encouragement, enhance, enhancement, enlarge,
   enlargement, enlighten, enliven, ennoblement, enrich, enrichment,
   erect, escalate, establish, eugenics, euthenics, exalt, exaltation,
   exhilarate, expand, expansion, expedite, extend, extension, extort,
   facilitate, fatten, favor, filch, fill out, flood, force, forward,
   foster, further, furtherance, gain, give a lift, give a write-up,
   give publicity, gladden, go straight, goad, good word, graduation,
   greatening, growth, gush, hand, hasten, head, headway, hearten,
   heave, heft, heighten, heist, help, helping hand, hike, hike up,
   hoick, hoist, hold up, honorable mention, hook, hurtle, hustle,
   hype, improve, improve upon, improvement, increase, increment,
   inflate, inflation, inspire, inspirit, invigorate, jab, jack up,
   jam, jerk up, jog, joggle, jolt, jostle, jump, jump up, knighting,
   knock up, lard, leap, leg, leg up, lend wings to, lengthen,
   levitate, lift, lift up, liven, lob, loft, magnify,
   make an improvement, make for, make off with, maximize, meliorate,
   melioration, mend, mending, mounting, multiplication, multiply,
   nip, nudge, nurture, palm, parlay, passing, pay raise, perk up,
   pick up, pickup, pile drive, pilfer, pinch, placard, plug, poach,
   poke, post, post bills, post up, preferment, press, press-agent,
   pressure, prod, productiveness, progress, progression,
   proliferation, promote, promotion, publicize, puff, punch, purloin,
   push, push forward, put forward, put up, pyramid, quicken, raise,
   raise up, ram, ram down, rattle, rear, rear up, recognition,
   recommend, recovery, refine upon, reform, rejoice,
   rejoice the heart, restoration, revival, rise, run, run against,
   run away with, rustle, scrounge, sell, set forward, set up, shake,
   shoplift, shoulder, shove, sky, snare, snatch, snitch, snowballing,
   socialize, speak highly of, speak warmly of, speak well of, speed,
   spiel, spread, steal, stick up, straighten out, stress, support,
   surge, swelling, swindle, swipe, take, tamp, thicken, thieve,
   throw up, thrust, tout, transfigure, transform, tumescence, up,
   upbeat, upbuoy, upcast, upgrade, upgrading, upheave, uphoist,
   uphold, uplift, upping, upraise, uprear, upsurge, upswing, upthrow,
   uptrend, upturn, upward mobility, vitalize, walk off with, wax,
   waxing, widening, write up