couldn't

USAGE SUMMARY

'couldn't' is a correct and usable word in written English
It is an informal contraction for the phrase “could not” and is used to show that something was not possible or did not happen in the past. For example: I couldn't believe what I was seeing.

✓ Grammatically correct

News & Media

Science

Academia

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Couldn't write.

Harvard University

Couldn't attend?

Massachusetts Institute of Technology

She couldn't.

Stanford University

Couldn't hurt.

Princeton University

I couldn't.

Princeton University

Some couldn't.

Princeton University

I couldn't, couldn't, couldn't function.

The Guardian - Sport

Couldn't he?

The New York Times

Couldn't tell.

The New Yorker

We couldn't.

The New York Times

Couldn't sleep".

The New York Times

Expert writing Tips

Best practice

Use "couldn't" in informal contexts where a contraction is appropriate to maintain a conversational tone.

Common error

Be careful not to use "couldn't" in a way that creates a double negative. For instance, avoid phrases like "I couldn't not go" when you mean "I had to go".

Linguistic Context

The primary grammatical function of "couldn't" is to express past inability or impossibility. As Ludwig AI indicates, it's a contraction of "could not", used to negate the possibility or ability to perform an action in the past. Examples such as "I couldn't sleep" or "They couldn't cope" clearly illustrate this function.

Expression frequency: Very common

Frequent in

News & Media

42%

Science

36%

Academia

22%

Less common in

Formal & Business

0%

Encyclopedias

0%

Wiki

0%

Ludwig's WRAP-UP

In summary, "couldn't" is a common contraction of "could not" used to express past inability or impossibility. As Ludwig AI states, it is grammatically correct and widely used in various contexts, ranging from news and media to scientific and academic writing, though it may be less appropriate for highly formal contexts. When using "couldn't", be mindful of avoiding double negatives and consider using more formal alternatives like "was unable to" in appropriate situations. It's a versatile term for conveying limitations and lack of past ability.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

was unable to

Replaces the contraction with a more formal expression of inability.

was not able to

A slightly more verbose and formal way of saying something was not possible.

found it impossible to

Highlights the impossibility of achieving something.

was incapable of

Indicates a fundamental inability to do something.

lacked the ability to

Focuses on the absence of a specific skill or ability.

did not have the capacity to

Emphasizes a lack of capacity or capability to perform an action.

did not succeed in

Focuses on the lack of success in performing a task.

failed to

A direct and simple way to express a lack of success.

was just not possible to

Emphasizes the impossibility from the point of view of feasibility.

it was beyond my power to

Highlights the lack of power or control to achieve something.

FAQs

How do you use "couldn't" in a sentence?

"Couldn't" is used to express the inability to do something in the past. For example, "I "couldn't believe it"" or "We "couldn't see anything"."

What's a more formal alternative to "couldn't"?

If you're looking for a more formal alternative, you can use "was not able to" or "was unable to". For example, instead of "I "couldn't attend"", you could say "I was unable to attend".

Is it ever incorrect to use "couldn't"?

While "couldn't" is generally correct in informal writing and speech, it might be considered less appropriate in highly formal or academic writing where contractions are discouraged.

What is the difference between "couldn't" and "wouldn't"?

"Couldn't" indicates an inability to do something, while "wouldn't" indicates a refusal or unwillingness. For example, "I "couldn't go" because I was sick" (inability), versus "I "wouldn't go" even if I were paid" (refusal).