once
- 01 A1 Beginner
adv.one time and only one time.
adv.on a single occasion; one time only.
Simple“I have only been to Paris once, but I would love to go back.”
In context“The medication should be administered once every twenty-four hours to maintain a consistent level in the bloodstream.”
UsageUsually placed after the verb or at the end of a clause.
Synonymsonce onlysinglyAntonyms - 02 A2 Elementary
adv.at a time in the past but not anymore.
adv.at a former time; formerly.
Simple“This building was once a school, but now it is a library.”
In context“The region was once a thriving industrial hub, though it has since transitioned into a service-based economy.”
UsageOften used to introduce stories or to describe a state that has changed.
Synonyms - 03 B2 Upper Intermediate
adv.multiplied by the number one.
adv.indicating that a quantity is multiplied by one.
Simple“Any number multiplied once by itself remains the same.”
In context“The formula requires the variable to be factored once before the final calculation is performed.”
UsageUsed in mathematical contexts to define identity or frequency.
- 04 B1 Intermediate
conj.as soon as or after something happens.
conj.as soon as; at the moment that.
Simple“Once you finish your homework, you can go outside and play.”
In context“Once the contract has been signed by both parties, the initial deposit will be transferred to the escrow account.”
UsageUsed to join two clauses; the 'once' clause usually happens first.
- 05 C1 Advanced
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.
Simple“She has been a dedicated Once since the band first started.”
In context“Thousands of Onces gathered outside the stadium hours before the concert began, trading photocards and singing along to the group's latest hits.”
Teacher's tipThis is a very specific cultural term used by fans of K-pop; it is not used in general or formal English.
Usage once again · once a week · once felt
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.