1. (adv.) By limitation to the number one; for one time; not twice nor any number of times more than one.

2. (adv.) At some one period of time; -- used indefinitely.

3. (adv.) At any one time; -- often nearly equivalent to ever, if ever, or whenever; as, once kindled, it may not be quenched.

alone already ancient anytime anyway anywise apart at a stroke at all at any time at intervals at once at one time at times at whatever time before by itself bygone conclusively decidedly definitely directly earlier early erstwhile finally for good fore former formerly heretofore if ever immediately immemorial in a jiffy in a trice in a wink in the singular individually instantly just this once late long ago no matter when now and again occasionally old olden on one occasion once for all one by one one day one fine morning one time onetime only once particularly past per se periodically positively prehistoric previous previously primeval primitive prior promptly quondam recent right away separately severally simultaneously single-handedly singly singularly some time ago sometime sometimes sporadically then time was together whenever whensoever whilom without delay