/wuns/ , 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.
10. former; having at one time been: the once and future king.
conj.
11. if or when at any time; if ever.
12. whenever; as soon as: Once you're finished, you can leave.
n.
13. a single occasion; one time only: Once is enough.
14. 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.
15. at once ,
a. at the same time; simultaneously: Don't all speak at once.
b. immediately; promptly: Tell him to come at once!
[ bef. 1150; ME ones, OE anes, orig. gen. of an ONE; r. ME enes, OE aenes once, equiv. to aene once (orig. instrumental of an ) + -es adv. suffix; see -S 1 ]