THESAURUS
Augment
add to, agent provocateur, aggrandize, aggravate, amplify, annoy, bloat, blow up, boost, broaden, build, build up, bulk, bulk out, compound, crescendo, deepen, deteriorate, develop, dilate, distend, embitter, enhance, enlarge, exacerbate, exalt, exasperate, expand, extend, fatten, fill out, fortify, heat up, heighten, hike, hike up, hot up, huff, increase, inflate, intensify, irritate, jack up, jump up, lengthen, magnify, make acute, make worse, manifold, maximize, mount, multiply, parlay, provoke, puff, puff up, pump, pump up, put up, pyramid, raise, rarefy, recruit, reinforce, rise, sharpen, sour, strengthen, stretch, sufflate, supplement, swell, thicken, up, upsurge, wax, widen, worsen
ROGET THESAURUS
Augment
Increase
VB
increase, augment, add to, enlarge, dilate, grow, wax, get ahead, gain strength, advance, run up, shoot up, rise, ascend, sprout, aggrandize, raise, exalt, deepen, heighten, strengthen, intensify, enhance, magnify, redouble, aggravate, exaggerate, exasperate, exacerbate, add fuel to the flame, oleum addere camino, superadd, spread.
Addition
VB
add, annex, affix, superadd, subjoin, superpose, clap on, saddle on, tack to, append, tag, ingraft, saddle with, sprinkle, introduce, insert, become added, accrue, advene, supervene, reinforce, reenforce, restrengthen, swell the ranks of, augment.
Adjunct
N
adjunct, addition, additament, additum, affix, appelidage, annexe, annex, augment, augmentation, increment, reinforcement, supernumerary, accessory, item, garnish, sauce, accompaniment, adjective, addendum, complement, supplement, continuation, rider, offshoot, episode, side issue, corollary, piece, flap, lappet, skirt, embroidery, trappings, cortege, tail, suffix, wing, additional, alate, alated, winged, in addition.