[ wuhns ]
See synonyms for once on Thesaurus.com
  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.

  1. even a single time; at any time; ever: If the facts once become known, it will be just too bad.

  2. by a single step, degree, or grade: a cousin once removed.

  1. former; having at one time been: the once and future king.

  1. if or when at any time; if ever.

  2. whenever; as soon as: Once you're finished, you can leave.

  1. a single occasion; one time only: Once is enough.

Idioms about once

  1. all at once,

    • simultaneously: The children were running, screaming, and throwing things all at once.

    • suddenly: All at once the rain came down.

  2. at once,

    • at the same time; simultaneously: Don't all speak at once.

    • immediately; promptly: Tell him to come at once!

  1. once and again, repeatedly: He has been told once and again not to slam the door.

  2. once and for all, decisively; finally: Let's settle this problem once and for all.: Also once for all.

  3. once in a while, at intervals; occasionally: She stops in to see us once in a while.

  4. once or twice, a very few times; infrequently: I've seen her in the elevator once or twice.

  5. once upon a time, at some unspecified past time, especially a long time ago: Once upon a time, in a faraway land, there lived a prince and princess.

Origin of once

First recorded before 1150; Middle English ones, Old English ānes, originally genitive of ān “one” replacing Middle English enes, Old English ǣnes “once,” equivalent to ǣne “once” (originally instrumental of ān ) + -es adverb suffix; see one, -s1

Words Nearby once

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use once in a sentence

British Dictionary definitions for once


/ (wʌns) /

  1. one time; on one occasion or in one case

  2. at some past time; formerly: I could speak French once

  1. by one step or degree (of relationship): a cousin once removed

  2. (in conditional clauses, negatives, etc) ever; at all: if you once forget it

  3. multiplied by one

  4. once and away

    • conclusively

    • occasionally

  5. once and for all conclusively; for the last time

  6. once in a while occasionally; now and then

  7. once or twice or once and again a few times

  8. once upon a time used to begin fairy tales and children's stories

  1. (subordinating) as soon as; if ever or whenever: once you begin, you'll enjoy it

  1. one occasion or case: you may do it, this once

  2. all at once

    • suddenly or without warning

    • simultaneously

  1. at once

    • immediately

    • simultaneously

  2. for once this time, if (or but) at no other time

Origin of once

C12 ones, ānes, adverbial genitive of on, ān one

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with once


In addition to the idioms beginning with once

  • once and for all
  • once bitten, twice shy
  • once in a blue moon
  • once in a lifetime
  • once in a while
  • once over lightly
  • once upon a time

also see:

  • all at once
  • at once
  • every now and then (once in a while)
  • give someone the once-over

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.