Антонимом a gradual

abrupt sudden broken instantaneous overnight discontinuous infrequent intermittent irregular rapid uneven immediate instant quick swift prompt hasty speedy expeditious hurried express fast snappy lightning unexpected precipitate unforeseen direct unanticipated fleet alacritous spontaneous rathe meteoric sharp impetuous rash impulsive precipitous explosive without warning on-the-spot without notice unlooked-for without delay not bargained for rushed unplanned unannounced unheralded out of the blue

steep sudden precipitous

noticeable discernible perceptible appreciable detectable discernable obvious palpable ponderable sensible visible apparent audible conspicuous distinct distinguishable evident seeable striking unobscured significant considerable

brief short fleeting momentary ephemeral passing prompt temporary fugacious quick swift transitory evanescent transient short-lived short-term

erratic arrhythmic desultory staggered unmeasured unrhythmic fluctuating inconsistent nonmetrical uneven unsettled unstable unsteady variable varying arbitrary haphazard inconstant irregular scattered unpredictable mercurial

clumsy heavy-handed

big huge important large rough significant substantial thick

hasty hurried quick speedy swift barreling bolting breakneck breathless brief brisk careering dizzy fast fleet flying hectic hurrying lightning meteoric racing rapid rocketing running rushed rushing scooting scudding scurrying snappy speeding warp-speed whirling whirlwind whisking zipping cursory impatient nervous

cohesive

a grain of agrammatical agraphia agrarian agrarian society a great amount agoraphobias agoraphobia a good way a good number a good memory a good few