What does "once" mean?

1. (one time only) one time and only one time. 2. (in the past) at a time in the past but not anymore. 3. (multiplied by one) multiplied by the number one. 4. (as soon as) as soon as or after something happens. 5. (fan of the band Twice) a name for a fan of the famous music group called Twice.

How do you use "once"?

Usually placed after the verb or at the end of a clause. Often used to introduce stories or to describe a state that has changed. Used in mathematical contexts to define identity or frequency. Used to join two clauses; the 'once' clause usually happens first.

once — meaning, definition & examples

Word

01one time only

A1 · Beginner

adv. one time and only one time.

adv. on a single occasion; one time only.

“I have only been to Paris once, but I would love to go back.”

“The medication should be administered once every twenty-four hours to maintain a consistent level in the bloodstream.”

Usage

Usually placed after the verb or at the end of a clause.

Synonyms

once onlysingly

Antonyms

twice repeatedly

02in the past

A2 · Elementary

adv. at a time in the past but not anymore.

adv. at a former time; formerly.

“This building was once a school, but now it is a library.”

“The region was once a thriving industrial hub, though it has since transitioned into a service-based economy.”

Usage

Often used to introduce stories or to describe a state that has changed.

Synonyms

formerly previously

Antonyms

currently now

03multiplied by one

B2 · Upper Intermediate Mathematics Technical

adv. multiplied by the number one.

adv. indicating that a quantity is multiplied by one.

“Any number multiplied once by itself remains the same.”

“The formula requires the variable to be factored once before the final calculation is performed.”

Usage

Used in mathematical contexts to define identity or frequency.

04as soon as

B1 · Intermediate

conj. as soon as or after something happens.

conj. as soon as; at the moment that.

“Once you finish your homework, you can go outside and play.”

“Once the contract has been signed by both parties, the initial deposit will be transferred to the escrow account.”

Usage

Used to join two clauses; the 'once' clause usually happens first.

Synonyms

when after

05fan of the band Twice

C1 · Advanced Countable noun Music Slang

n. a name for a fan of the famous music group called Twice.

n. a member of the official fandom for the South Korean girl group Twice.

“She has been a dedicated Once since the band first started.”

“Thousands of Onces gathered outside the stadium hours before the concert began, trading photocards and singing along to the group's latest hits.”

Teaching tip

This is a very specific cultural term used by fans of K-pop; it is not used in general or formal English.

Common phrases and expressions where native English speakers use the word “once” in context.

01. once again 02. once a week 03. once felt 04. once thought 05. once used 06. once believed 07. once considered 08. once existed

From Middle English ones, from Old English ānes, a remodelling (after ān (“one”)) of ǣnes, itself an extension of ǣne (“once”) with the genitive suffix -es. Equivalent to one + -s. Cognate with Saterland Frisian enst, insen (“once”), West Frisian iens (“once”), Dutch eens (“once”), German Low German eens, ins (“once”), German einst (“once”). More at one (including regarding the development of the pronunciation) and -s.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

at once frequency number one twice