Idioms

Origin of once

before 1150; Middle English ones, Old English ānes, orig. genitive of ān one; replacing Middle English enes, Old English ǣnes once, equivalent to ǣne once (orig. instrumental of ān) + -es adv. suffix; see -s1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for at once

once

/ (wʌns) /

adverb


conjunction

(subordinating) as soon as; if ever or wheneveronce you begin, you'll enjoy it

noun

Word Origin for 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

Idioms and Phrases with at once (1 of 2)

at once

1

At the same time, as in We can't all fit into the boat at once. [First half of 1200s] Also see at one time, def. 1.


2

Immediately, as in Mother told the children to come inside at once. [First half of 1500s]

Idioms and Phrases with at once (2 of 2)

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.