once
once / wəns/ • adv. 1. on one occasion or for one time only: they deliver once a week. ∎ at all; on even one occasion (used for emphasis): he never once complained if she once got an idea in her head you'd never move it.2. at some time in the past; formerly: He had once been an Army officer.• conj. as soon as; when: once the grapes were pressed, the juice was put into barrels.PHRASES: all at once1. without warning; suddenly: all at once the noise stopped.2. all at the same time: scared and excited all at once.at once1. immediately: I fell asleep at once.2. simultaneously: computers that can do many things at once.for once (or this once) on this occasion only, as an exception: He was glad that for once he had not listened.once again (or more) one more time.once and for all (or once for all) now and for the last time; finally.once and future denoting someone or something that is eternal, enduring, or constant.once bitten, twice shy see bite.once (or every once) in a while from time to time; occasionally.once or twice a few times.once upon a time at some time in the past (used as a conventional opening of a story). ∎ formerly: once upon a time she would have been jealous, but no longer.