once when

USAGE SUMMARY

'once when' is a correct and usable phrase in written English.
It is used to refer to a singular past event that occurred at some uncertain point in time, as in the following example sentence: Once when I was a child, I went on a camping trip with my family.

✓ Grammatically correct

News & Media

Science

Formal & Business

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Once, when discussing the former L.S.U.

The New York Times

Once when he crashes his car, twice.

The Guardian

Once, when I signed to MCA.

The Guardian - Music

Except once, when he eventually does.

The Guardian

"Once when my mother died and once when the World Trade Center collapsed.

The New York Times

Only once, when she was 10, did the family evacuate.

The New York Times

Once when she was younger she killed a dog.

The New Yorker

"Once, when I saw a house I wanted to buy.

The New Yorker

Once, when a new head of nursing at U.C.S.F.

The New Yorker

I visited him there once, when I was 14.

The New York Times

Once, when Gingrich was fifteen, he stayed out past curfew.

The New Yorker

Expert writing Tips

Best practice

Use "once when" to clearly indicate a single event that occurred in the past under specific circumstances. This phrasing helps to provide context and timing to the event being described.

Common error

Do not overuse "once when" in close proximity to other time-related phrases; this can create ambiguity. Ensure the context clearly distinguishes the single event you are referencing.

Linguistic Context

The phrase "once when" functions as a temporal adverbial clause, specifying a single occasion in the past. It introduces a dependent clause that provides context or sets the stage for the main clause. Ludwig confirms it with several real-world examples.

Expression frequency: Very common

Frequent in

News & Media

50%

Science

25%

Formal & Business

10%

Less common in

Wiki

10%

Encyclopedias

3%

Reference

2%

Ludwig's WRAP-UP

The phrase "once when" is a common and grammatically sound construction used to describe a specific instance in the past. As confirmed by Ludwig, it functions as a temporal adverbial clause, adding context and detail to narratives across various registers, primarily in news and media, science, and formal business contexts. While its usage is straightforward, ensuring clarity and avoiding overuse are key to effective communication.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

one time when

Replaces "once" with "one time", emphasizing the singularity of the event.

on one occasion when

Adds formality by using "on one occasion" instead of "once".

a single instance when

Highlights the uniqueness of the event with "a single instance".

at one point when

Emphasizes a specific moment in time.

during that time when

Focuses on the period when the event occurred.

in that moment when

Highlights the exact instant the event happened.

as soon as

Expresses immediacy, implying the event happened right after a condition was met.

the moment that

Emphasizes the specific timing of the event.

when it happened that

A more descriptive and slightly verbose alternative, focusing on the event itself.

at the time that

Indicates the event took place concurrently with another.

FAQs

How can I use "once when" in a sentence?

The phrase "once when" is used to introduce a specific instance or occasion in the past. For example: "Once when I was younger, I visited Paris."

What phrases are similar to "once when"?

Similar phrases include "one time when", "on one occasion when", or "a single instance when", all of which emphasize a unique event in the past.

Is it grammatically correct to use "once when"?

Yes, "once when" is grammatically correct. It is used to specify that something happened a single time under particular circumstances. Ludwig AI confirms it with several real-world examples.

What's the difference between "once when" and "when"?

"When" refers to a general time or circumstance, while "once when" refers to a specific, singular occurrence. Using "once when" adds emphasis to the uniqueness of the event in question.