Synonyms and related words :
abrupt, accident-prone, acclivitous, arduous, bluff, bold, breakneck, breathless, careless, declivitous, desperate, devil-may-care, electrifying, furious, harum-scarum, hasty, headlong, hotheaded, hurried, impetuous, impulsive, mad, nerve-shattering, orthodiagonal, orthogonal, overeager, overenthusiastic, overzealous, panting, perpendicular, plumb, plunging, precipitant, precipitate, quick, rapid, rash, reckless, right-angle, right-angled, right-angular, rushing, sharp, sheer, shocking, sideling, slap-bang, slapdash, speedy, startling, steep, stickle, straight-up, straight-up-and-down, sudden, surprising, swift, unanticipated, unexpected, unforeseen, unlooked-for, unpredicted, up-and-down, vertical, wanton, wild