could

could — modal verb

1. used when talking about what a person or thing was able to do on a particular oc

1.modal verbA1
Definition

used when talking about what a person or thing was able to do on a particular occasion in the past, or about a skill or natural ability someone had before now

Example

When I was six, I could already read simple storybooks by myself.

The swimmer could hold her breath for nearly two minutes.

Common collocations
  • could hear
  • could see
  • could speak
  • could barely
  • could easily
  • could hardly
Synonyms
  • was able to

    more formal; also used for single past achievements where 'could' may sound unnatural

  • managed to

    emphasises effort or difficulty overcome in a specific situation

Antonyms

Grammar Patterns

could + base form (affirmative)

could not / couldn't + base form (negative)

could + subject + base form? (question)

Usage Note

For the present tense, use 'can' instead of 'could'. In affirmative sentences about a single past achievement ('managed to'), 'was/were able to' is more common than 'could'.

Common Mistakes

Yesterday I can swim across the lake.
Yesterday I could swim across the lake.
Use 'could' (not 'can') for past ability.
He could to run fast when he was young.
He could run fast when he was young.
Do not add 'to' after a modal verb.

2. used as a polite way to ask for permission to do something — softer and more hes

2.modal verbA1
Definition

used as a polite way to ask for permission to do something — softer and more hesitant than 'can', which some listeners may find too direct

Example

Could I open the window? It feels a bit stuffy in here.

polite request for permission: Could I + verb

Could we leave a little earlier today? I have a doctor's appointment.

Common collocations
  • could I
  • could we
  • could I possibly
  • do you think I could
Synonyms
  • can

    less polite, used in informal situations

  • may

    more formal, common in official or written contexts

Grammar Patterns

Could + I/we + base form? (asking for permission)

Could + I/we + possibly + base form? (more hesitant)

Usage Note

This sense always appears in question form. 'Could' is more polite than 'can', while 'may' is slightly more formal. In spoken English, 'Can I…?' is also acceptable but less courteous.

Common Mistakes

Could I to borrow your pen?
Could I borrow your pen?
Do not add 'to' after a modal verb.

3. used as a courteous way of asking another person to take a particular action — s

3.modal verbA1
Definition

used as a courteous way of asking another person to take a particular action — softer in tone than the more direct 'can'

Example

Could you please pass me the salt? I can barely reach it.

Could you please + verb (standard polite request)

Could you help me move this table to the other side of the room?

Common collocations
  • could you
  • could you please
  • could you possibly
  • could you just
Synonyms
  • can

    less polite; sounds more like an instruction than a request

  • would

    similar politeness level; 'would you' can sound slightly more hypothetical

Grammar Patterns

Could + you + please + base form? (polite request)

Could + you + possibly + base form? (more hesitant request)

Usage Note

Like sense 2, this always takes question form. The addressee is almost always 'you'. Adding 'please' makes the request warmer. To sound even more hesitant or apologetic, use 'Could you possibly…?'

Common Mistakes

Could you to open the door?
Could you open the door?
Never insert 'to' between a modal and the main verb.

❌ 'Could you give me a hand?' (acceptable) — This is actually fine; just avoid 'to'.

4. used to say that something is possible or might happen, especially when you are

4.modal verbA2
Definition

used to say that something is possible or might happen, especially when you are not certain or when the chance is not strong

Example

The traffic could be really bad on a Friday afternoon.

Don't throw that box away — it could be useful for storage.

possibility: could + be + adjective

Common collocations
  • could be
  • could become
  • could mean
  • could happen
  • could possibly
  • could easily
Synonyms
  • might

    similar level of possibility; often interchangeable with 'could'

  • may

    slightly more formal and can imply a marginally higher chance

  • can

    used for general possibility; 'could' sounds more tentative about a specific case

Antonyms

Grammar Patterns

could + base form (present/future possibility)

could + have + past participle (past possibility that did not happen)

could + be + -ing (present possibility)

Usage Note

To express a stronger degree of certainty, use 'may' or 'might'. 'Could' suggests a real but not confidently expected possibility. For past possibilities that did not actually happen, use 'could have + past participle': 'You could have hurt yourself.'

Common Mistakes

It could rains tomorrow.
It could rain tomorrow.
After a modal verb, use the base form of the main verb, not an -s form.

5. used to make a suggestion or offer an idea about what someone might do, either f

5.modal verbA2
Definition

used to make a suggestion or offer an idea about what someone might do, either for their own benefit or as a shared plan

Example

You could try calling her again later this evening.

suggestion: you could + try + -ing

We could take the scenic route along the coast instead of the highway.

Common collocations
  • you could
  • we could
  • could try
  • could always
  • could also
  • could just
Synonyms
  • might

    in suggestion contexts, 'might' sounds slightly more formal: 'You might want to try…'

  • should

    stronger and more directive; suggests a moral obligation or strong recommendation

Grammar Patterns

You/We could + base form (suggestion)

We could always + base form (alternative suggestion)

You could try + -ing / noun (suggestion with try)

Usage Note

Unlike sense 4 (POSSIBILITY), this sense offers a course of action the listener could choose. In questions ('Could we…?'), it overlaps with making a tentative suggestion. To make the suggestion stronger or more definite, use 'should' or 'ought to'.

Common Mistakes

You could to try the new restaurant.
You could try the new restaurant.
Never add 'to' after 'could'.

6. expressing irritation or disappointment that a person failed to carry out an act

6.modal verbB1
Definition

expressing irritation or disappointment that a person failed to carry out an action the speaker believes was reasonably expected of them

Example

You could have told me you were not coming to the party.

could have + past participle for past criticism

João could have asked before borrowing his brother's car.

Common collocations
  • could have
  • could at least have
  • could easily have
Synonyms
  • should have

    stronger sense of duty or moral obligation; 'could have' focuses on missed opportunity or reasonable expectation

Grammar Patterns

could + have + past participle (criticism about a past inaction)

could + at least + have + past participle (emphasising minimum expected action)

Usage Note

This sense almost always uses 'could have + past participle' referring to a past action that the speaker believes was expected. In speech, 'could have' is usually contracted to 'could've' (/ˈkʊd.əv/). The tone ranges from mild disappointment to strong anger depending on intonation.

Common Mistakes

You could of told me earlier.
You could have told me earlier.
'Could of' is a common misspelling of the contracted form 'could've'. Never write 'of' after 'could'.
Idioms

could do with

idiom

to need or want something very much; to feel that something would improve a situation

After walking all day in the summer heat, we could do with a cold drink and a rest.

This room could do with more light — the curtains are too heavy and dark.

could do without

idiom

to not want something because it is annoying or causes problems; to prefer to avoid something

I could do without the noise from the construction site outside my window.

We could do without another argument about whose turn it is to wash the dishes.

couldn't care less

idiom

used to say very strongly that something is not important to you at all and you have no interest in it

Aaron said he could not care less about which team wins the game.

Zola could not care less whether her phone has the latest features or not.

couldn't agree more

idiom

used to express full agreement with someone — a way of saying you share exactly the same opinion

"I think children should spend more time playing outdoors." "I could not agree more."

Christopher could not agree more with the idea of reducing plastic waste.

could do with something

idiom

It means you need or want something very much.

After working all day, I could do with a hot bath.

This room could do with a fresh coat of paint.

Word family

  • can
    modal verbA1
  • cannot
    modal verbA1
  • can't
    modal verbA1
  • couldn't
    modal verbA1
  • be able to
    phraseA1

Synonym discussion

Sense: modal verb/4

These four modal verbs all express possibility, but they differ in degree of certainty and formality. 'Could' suggests a real possibility that is not strongly expected: 'The train could be late.' 'Might' conveys similar uncertainty but often feels slightly more tentative or remote: 'It might rain later.' 'May' is more formal than both and often implies a slightly higher chance from the speaker's perspective: 'The results may surprise you.' 'Can' expresses general or theoretical possibility — what is sometimes true or typical — rather than a specific uncertain event: 'It can rain a lot in April.' In everyday conversation, 'could' and 'might' are largely interchangeable for tentative possibility. For past events that did not happen, only 'could have' works: 'She could have won the race.' Use 'may have' or 'might have' when the past event's truth is still unknown: 'She may have already left.'

could ↗might ↗may ↗can ↗

Common collocations

Adverbs

  • could possibly
  • could easily
  • could barely
  • could hardly
  • could certainly
  • could just
  • could always
  • could at least

Phrases

  • could be that
  • could have been
  • could it be that
  • as far as I could

Prepositions

Etymology

Old EnglishMiddle EnglishEnglish

'Could' began in Old English as 'cūðe', the past tense of 'cunnan', which meant 'to know' or 'to know how to'. Over time, 'cunnan' developed the meaning of 'be able to'. In Middle English, an extra ⟨l⟩ was added by analogy with 'would' and 'should' — both of which already contained an ⟨l⟩ — even though 'could' had never had one. This spelling change stuck, though the ⟨l⟩ remains silent today.