THESAURUS
Improvise
ad lib, ad-lib, be caught napping, be surprised, be taken unawares, be unprepared, beget, breed, bring forth, bring into being, call into being, coin, conceive, concoct, contrive, cook up, dash off, design, develop, devise, discover, do offhand, dream up, engender, evolve, extemporize, fabricate, fake, frame, generate, give being to, give rise to, go off half-cocked, hatch, have no plan, improvisate, invent, jury-rig, knock off, lash up, make do, make do with, make up, mature, mint, originate, plan, play by ear, procreate, scrap the plan, spawn, strike off, strike out, think out, think up, throw off, throw together, toss off, toss out, vamp, whip up, whomp up, wing it
ROGET THESAURUS
Improvise
Impulse
VB
flash on the mind, say what comes uppermost, improvise, extemporize, give an impetus, impel, push, start, give a start to, set going, drive, urge, boom, thrust, prod, foin, cant, elbow, shoulder, jostle, justle, hustle, hurtle, shove, jog, jolt, encounter, run against, bump against, butt against, knock one's head against, run one's head against, impinge, boost, bunt, carom, clip y, fan, fan out, jab, plug, strike, knock, hit, tap, rap, slap, flap, dab, pat, thump, beat, blow, bang, slam, dash, punch, thwack, whack, hit hard, strike hard, swap, batter, dowse, baste, pelt, patter, buffet, belabor, fetch one a blow, poke at, pink, lunge, yerk, kick, calcitrate, butt, strike at, whip, come into a collision, enter into collision, collide, sideswipe, foul, fall foul of, run foul of, telescope, throw.
N
impulse, sudden thought, impromptu, improvisation, inspiration, flash, spurt, improvisatore, creature of impulse, extemporaneous, impulsive, indeliberate, snap, improvised, improvisate, improvisatory, unpremeditated, unmeditated, improvise, unprompted, unguided, natural, unguarded, spontaneous, instinctive, extempore, extemporaneously, offhand, impromptu, a limproviste, improviso, on the spur of the moment, on the spur of the occasion, impulse, impulsion, impetus, momentum, push, pulsion, thrust, shove, jog, jolt, brunt, booming, boost, throw, explosion, propulsion, percussion, concussion, collision, occursion, clash, encounter, cannon, carambole, appulse, shock, crash, bump, impact, elan, charge, beating, blow, dint, stroke, knock, tap, rap, slap, smack, pat, dab, fillip, slam, bang, hit, whack, thwack, cuff, squash, dowse, swap, whap, punch, thump, pelt, kick, punce, calcitration, ruade, arietation, cut, thrust, lunge, yerk, carom, carrom, clip, jab, plug, sidewinder, sidewipe, sideswipe, hammer, sledge hammer, mall, maul, mallet, flail, ram, rammer, battering ram, monkey, pile-driving engine, punch, bat, cant hook, cudgel, ax, dynamics, seismometer, accelerometer, earthquake detector, impelling, impulsive, impellent, booming, dynamic, dynamical, impelled, a hit, a very palpable hit.
Nonpreparation
VB
be unprepared, want preparation, lack preparation, lie fallow, s'embarquer sans biscuits, live from hand to mouth, dismantle, undress, extemporize, improvise, ad lib.
Imagination
VB
imagine, fancy, conceive, idealize, realize, dream, dream of, dream up, give to airy nothing a local habitation and a name, create, originate, devise, invent, coin, fabricate, improvise, strike out something new, set one's wits to work, strain one's invention, crack one's invention, rack one's brains, ransack one's brains, cudgel one's brains, excogitate, brainstorm, give play, give the reins, give a loose to the imagination, give fancy, indulge in reverie, visualize, envision, conjure up a vision, fancy oneself, represent oneself, picture, picture-oneself, figure to oneself, vorstellen, float in the mind, suggest itself.