Synonyms of once in English:


See US English definition of once

See UK English definition of once


1‘I saw him only once’

on one occasion, one time, one single time

twice, many times

2‘he did not once help’

ever, at any time, on any occasion, at all, under any circumstances, on any account, in a million years

3‘they were friends once’

formerly, previously, in the past, at one time, at one point, once upon a time, on a former occasion, on one occasion, one time, in one case, time was when, in days gone by, in times gone by, back in the day, in times past, in the old days, in the good old days, long ago
archaic sometime, erst, erstwhile, whilom
literary in days of yore, in times of yore, of yore



1‘he'll be all right once she's gone’

as soon as, when, after, immediately after, the instant, the minute, the moment, the second
British informal immediately


    once and for all

    1‘you must decide once and for all’

    conclusively, decisively, finally, positively, absolutely, determinedly, definitely, definitively, irrevocably

    2‘he has gone once and for all’

    for good, for always, forever, permanently, finally, in perpetuity
    informal for keeps
    once in a while

    ‘once in a while a car went past’

    occasionally, from time to time, now and again, now and then, every now and again, every now and then, every so often, every once in a while, on occasion, on occasions, on the odd occasion, at times, sometimes, off and on, at intervals, periodically, sporadically, spasmodically, erratically, irregularly, intermittently, by fits and starts, in fits and starts, fitfully, discontinuously, piecemeal
    rare interruptedly
    at once

    1‘you must leave at once’

    immediately, right away, right now, this instant, this minute, this moment, this second, now, straight away, instantly, instantaneously, directly, suddenly, abruptly, summarily, forthwith, promptly, without delay, without hesitation, without further ado
    quickly, as fast as possible, as soon as possible, fast, speedily, with all speed
    informal like a shot, in a flash, like a flash, before you can say Jack Robinson, in two shakes, in two shakes of a lamb's tail

    later, in due course

    2‘all the guests arrived at once’

    at the same time, at one and the same time, at the same instant, at the same moment, together, all together, simultaneously
    as a group, in unison, in concert, in chorus

    singly, in dribs and drabs