instant

1 done or occurring without any noticeable lapse in time an instant response to the cry for help Synonyms immediate, instantaneous, split-second, straightawayRelated Words summary; fast, hit-and-run, prompt, quick, rapid, speedy, swiftNear Antonyms dilatory, tardy; slow, sluggish; prolonged, protracted; deferred, delayed

2 needing immediate attention an instant need for food supplies in the famine-stricken country Synonyms burning, clamant, compelling, critical, crying, dire, emergent, exigent, imperative, imperious, importunate, acute, necessitous, pressing, urgentRelated Words demanding, extreme, immediate, insistent, intense, overriding; crucial, desperate, grave, life-and-death (also life-or-death), serious, severe, vital; dangerous, explosive, hazardous, perilous, precarious, unstableNear Antonyms incidental, low-pressure, minor, negligible, trivial, unimportant; nonthreatening, safe, stableAntonyms noncritical, nonurgent

3 existing or in progress right now we should be more concerned with instant dangers than with those in the far-off future Synonyms current, extant, immediate, present, ongoing, present-dayRelated Words contemporary, mod, modern, modernistic, new, newfangled, new-fashioned, recent, red-hot, space-age, supermodern, ultramodern, up-to-date; being, breathing, existent, existing, livingNear Antonyms coming, future, unborn; completed, concluded, done, ended, finished, over, terminated, through, up; ancient, antediluvian, antiquated, antique, archaic, dated, fusty, musty, noncontemporary, obsolete, old, oldfangled, old-fashioned, old-time, out-of-date, outworn, passé; ago, bygone, erstwhile, former, past

a very small space of time it all happened in an instant Synonyms beat, eyeblink, flash, heartbeat, jiff, jiffy, minute, moment, nanosecond, New York minute, second, shake, split second, trice, twinkle, twinkling, wink Related Words microsecond; snatch, spurt Near Antonyms aeon (or eon), age, eternity, forever; infinity, lifetime