/ kəd; NAmE ; strong form kʊd/ modal verb ( negative could not , short form couldn't / ˈkʊdnt; NAmE /)
1.
used as the past tense of 'can' :
She said that she couldn't come.
I couldn't hear what they were saying.
Sorry, I couldn't get any more.
➡ note at can (I)
2.
used to ask if you can do sth :
Could I use your phone, please?
Could we stop by next week?
3.
used to politely ask sb to do sth for you :
Could you babysit for us on Friday?
4.
used to show that sth is or might be possible :
I could do it now, if you like.
Don't worry—they could have just forgotten to call.
You couldn't have left it on the bus, could you?
'Have some more cake.' 'Oh, I couldn't, thank you (= I'm too full) .'
5.
used to suggest sth :
We could write a letter to the director.
You could always try his home number.
6.
used to show that you are annoyed that sb did not do sth :
They could have let me know they were going to be late!
7.
( informal ) used to emphasize how strongly you want to express your feelings :
I'm so fed up I could scream!
➡ note at modal
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IDIOMS
- could do with sth