could

couldmodal verb

Could is used for past general ability, for possibility that is less certain than can, and as a polite way to ask or suggest.

1. was able to, in generalused as the past of can, to say that someone was able to do something in general

   Could describes a general skill or ability in the past. For one particular action that was actually completed, use was/were able to or managed to, not could, in the affirmative: she was able to open the door, not she could open the door. In the negative, couldn't works for both general and one-time inability.

   verb + bare infinitive [V + inf]

   • When I was young, I could run very fast. V + inf
   • She couldn't swim until she was ten. V + inf
   • He could speak three languages by the age of twelve. V + inf
   • We couldn't hear the announcement over the noise. V + inf (one-time inability, still couldn't)

   Compare can (can is the present form; could is the past); able (was able to is needed, not could, for one particular completed action)

   For translators (sense 1)

   Grammar trap Could on its own reports general ability in the past; one specific successful action needs was/were able to or managed to instead.

2. polite requestused as a polite way to ask someone to do something or to ask for something

   More polite than can, and common with people you do not know well or in formal situations.

   verb + bare infinitive [V + inf] polite

   • Could you pass the salt, please? V + inf (request)
   • Could I ask you a question? V + inf (request)
   • Could you speak a little more slowly? V + inf (request)

   Compare can (could is more polite and less direct than can for a request)

3. possible, but not certainused to say that something is possible now or in the future, though not certain

   Used to hedge a specific guess about the present or future, rather than stating a general fact (compare can, for what is generally or habitually possible).

   verb + bare infinitive [V + inf]

   • It could rain later. V + inf
   • She could be at home by now. V + inf
   • Prices could rise again next year. V + inf

   Synonyms may (close in meaning; may is a little more formal)

   Compare may; might (close in meaning; often used interchangeably)

   1. aused to offer or suggest something as one possibility among others

      • We could go to the beach, or we could stay home.
      • You could try calling her instead of texting.

4. could haveused with have and a past participle to say that something was possible in the past, whether or not it is known to have actually happened

   Could have often talks about a past possibility that was not realized, with a note of regret, criticism, or relief; it can also guess about an outcome the speaker does not actually know. Compare should have, which judges that something was the right thing to do.

   • You could have told me you were going to be late!
   • She could have won if she had trained harder.
   • We could have missed the flight; we were lucky.
   • She could have left already; I haven't checked. (an unknown outcome, not a missed opportunity)

   Compare should (should have judges that something was the right thing to do; could have only says it was possible)

   For translators (sense 4)

   Grammar trap Could have is followed by a past participle, not a bare infinitive: could have gone, not could have go. In speech it often sounds like could of, but that spelling is wrong.

See also can; should (should have for judging what was the right thing to do)