could

USAGE SUMMARY

The word “could” is correct and usable in written English.
You can use it to express possibility, ability, or permission in the past. For example: I could finish my project in a week if I worked hard enough.

✓ Grammatically correct

News & Media

Formal & Business

Science

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

What could possibly go wrong?

The New York Times - Arts

I could not breathe.

The New York Times

As an environmentalist, and someone who believes that everyone in this world has a right to a healthy and nutritious diet of their choosing, I could not have chosen a more counter-productive path.

The New York Times

But it could have been".

The New York Times

"Although the investigation is in its early stages, we will take action to protect the public if we uncover evidence that could affect the safety of other rides at the park or elsewhere".

The Guardian

The grievances aren't unreasonable, on either side, but the focus on fairness, by making it harder to reach any kind of agreement at all, could prove disastrous.

The New York Times

This could not be further from the truth.

The New York Times

If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone, I would also do that.

The New York Times

I wish I could".

The New York Times

What could go wrong?

The New York Times

Such a development could pose a new threat to the isolated country's neighbours and the United States.

The Guardian

Expert writing Tips

Best practice

Use "could" to express polite requests or suggestions, especially when addressing someone formally. For example, "Could you please pass the salt?" is more courteous than "Can you pass the salt?"

Common error

Avoid using "could" when you actually mean "should". "Could" indicates possibility or ability, while "should" expresses obligation or recommendation. For instance, instead of "You could study harder", use "You should study harder" to convey advice.

Linguistic Context

The word "could" functions primarily as an auxiliary verb, expressing possibility, past ability, or polite requests. Ludwig examples show it qualifying actions and states, indicating potential or conditional outcomes. This aligns with the Ludwig AI’s assessment of its grammatical correctness.

Expression frequency: Very common

Frequent in

News & Media

44%

Formal & Business

28%

Science

28%

Less common in

Encyclopedias

0%

Wiki

0%

Reference

0%

Ludwig's WRAP-UP

In summary, "could" is a versatile auxiliary verb primarily used to express possibility, past ability, and polite requests. As Ludwig AI confirms, it is grammatically correct and widely accepted in written English. Its frequency is very common, appearing across diverse contexts from news articles to formal documents. While "could" is generally neutral, it's important to distinguish it from "should" to avoid miscommunication. Remember that "could" suggests possibility, whereas "should" implies obligation or recommendation.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

might

Expresses a lower degree of certainty or possibility than "could".

may

Similar to "might" in expressing possibility, often used for formal permissions.

would be able to

Emphasizes the ability to do something under specific conditions.

was able to

Indicates past ability or capacity to do something.

is it possible to

Phrases the idea as a question of possibility or feasibility.

is capable of

Highlights inherent ability or potential.

has the potential to

Focuses on the potential for something to happen or be achieved.

is permitted to

Implies formal authorization or allowance.

can

Expresses present ability or general possibility; less polite than "could" when asking for permission.

it is conceivable that

Suggests that something is imaginable or believable, though perhaps unlikely.

FAQs

How can I use "could" in a sentence?

"Could" is versatile. It can express past ability (e.g., "I could run fast when I was younger"), polite requests (e.g., "Could you help me?"), or possibility (e.g., "It could rain tomorrow").

What is the difference between "could" and "can"?

"Can" generally indicates present ability or possibility, while "could" often refers to past ability or a more polite or conditional possibility. "Can I borrow your pen?" is less formal than "Could I borrow your pen?".

When should I use "could have"?

"Could have" expresses a possibility that did not happen. For example, "I could have gone to the party, but I was too tired." It implies that you had the ability or opportunity, but you chose not to take it.

What are some alternatives to "could" for expressing possibility?

Depending on the context, you could use "might", "may", or "it is possible that". Each has slightly different nuances of probability and formality.