Synonyms and antonyms of Happening only once in American Thesaurus

once (adverb)

on one occasion only

isolated (adjective)

happening only once, or existing only in one place

unrepeatable (adjective)

something that is unrepeatable can only be done once or not very often because it is very special

one-off (adjective)

British happening, done, or made only once

once in a lifetime ()

a once in a lifetime experience is very unusual or special

in/at one fell swoop ()

with one sudden action, or on one single occasion

one-shot (adjective)

happening or done once and not repeated

one-off (noun)

British something that only happens once

(just) this once ()

used for emphasizing that this is the only time that something will happen