Synonyms and related words :
a bit previous, abrupt, accident-prone, ad-lib, advanced, agile, antsy, antsy-pantsy, anxious, bearish, brash, breakneck, breathless, brief, brisk, careless, caught napping, caught off balance, caught short, chafing, choleric, combustible, contentious, cranky, cursory, dashing, desperate, devil-may-care, double-quick, eager, eagle-winged, edgy, electrifying, excited, expeditious, explosive, express, extemporaneous, extemporized, far ahead, fast, festinate, feverish, fiery, fleet, fleeting, flying, forward, fretful, fretting, furious, galloping, hair-trigger, half-baked, half-cocked, haphazard, harum-scarum, headlong, heedless, hopped-up, hot, hot-tempered, hotheaded, hurried, hustling, ill-advised, ill-considered, immediate, impatient, impetuous, impromptu, improvised, impulsive, in a lather, in a stew, in a sweat, incautious, inconsiderate, instant, instantaneous, irascible, irritable, last-minute, light of heel, light-footed, lively, mad, madcap, makeshift, mercurial, momentary, nerve-shattering, nimble, nimble-footed, not firm, on edge, on the spot, overeager, overenthusiastic, overhasty, oversoon, overzealous, passing, passionate, peppery, perfunctory, petulant, precipitant, precipitate, precipitous, precocious, premature, previous, prompt, quick, quick as lightning, quick as thought, quick-tempered, rapid, rash, reckless, restive, restless, rough-and-ready, running, rushed, rushing, shocking, short-tempered, slap-bang, slapdash, snap, snappy, spanking, speedy, splenetic, spunky, squirming, squirmy, startling, sudden, superficial, surprised, surprising, swift, taken aback, taken by surprise, taken unawares, testy, thoughtless, too early, too soon, tripped up, unanticipated, unarranged, unbegun, unconcocted, uncontrived, uncrystallized, undeliberated, undevised, uneasy, unexpected, unforeseen, unhatched, unjelled, unlooked-for, unmade, unmanufactured, unmatured, unmeditated, unorganized, unpatient, unplanned, unpredicted, unpremeditated, unprepared, unprimed, unquiet, unready, unripe, unstudied, unthinking, untimely, urgent, volatile, volcanic, wanton, waspish, wild, winged