Pronunciation: (wuns),[key] —adv. 1. at one time in the past; formerly: I was a farmer once; a once powerful nation. 2. a single time: We ate there just once. We go to a movie once a week. 3. even a single time; at any time; ever: If the facts once become known, it will be just too bad. 4. by a single step, degree, or grade: a cousin once removed. 5. once and again, repeatedly: He has been told once and again not to slam the door. 6. once and for all, decisively; finally: Let's settle this problem once and for all.Also,once for all. 7. once in a while, at intervals; occasionally: She stops in to see us once in a while. 8. once or twice, a very few times; infrequently: I've seen her in the elevator once or twice. 9. once upon a time, at some unspecified past time, esp. a long time ago: Once upon a time, in a faraway land, there lived a prince and princess.
—adj. former; having at one time been: the once and future king.
—conj. 1. if or when at any time; if ever.
2. whenever; as soon as: Once you're finished, you can leave.
—n. 1. a single occasion; one time only: Once is enough. 2. all at once, a. simultaneously: The children were running, screaming, and throwing things all at once. b. suddenly: All at once the rain came down. 3. at once, a. at the same time; simultaneously: Don't all speak at once. b. immediately; promptly: Tell him to come at once!