could 
/ˈkʊd, kəd/ verb
/ˈkʊd, kəd/ verb [modal verb] 1 — used as the past tense of can ▪ When I was younger I could run fast, but I can't run fast now. ▪ Years ago you could buy a record album for a quarter. ▪ The car cost more than I could afford, so I bought a cheaper model. ▪ From where we stood, we could see for miles. ▪ She could be very rude at times. [=she was sometimes very rude] ▪ He never could quite fit in with the group. ▪ She said we could do whatever we wanted. [=she said, “You can do whatever you want.”] ▪ How could something like this happen? usage 1can 2 a — used to say that something is possible ▪ You could [=might, may] be making the biggest mistake of your life! ▪ This could be our only chance to get our of here. ▪ His recovery could take months. ▪ This medicine could help your cold. ▪ The evidence is not conclusive, but he could (very well) be right. ▪ This news could mean trouble. ▪ Did you think he could still be alive? ▪ That kind of thing could happen to anyone. ▪ They could still succeed, although it's not likely. ▪ I think he could be trying to cheat us. ▪ Do you think he could [=can] really be serious? ▪ Could this be our ride? [=is this our ride?]
b — used with have to say that something was possible but did not actually happen ▪ You could have been seriously hurt. ▪ The accident could have been worse. ▪ The movie could have been better. [=the movie wasn't very good] ▪ They could have succeeded if they had worked harder. ▪ The error could have lost the game for them. ▪ We could just as easily have fixed the engine ourselves.
c — used to talk about something that is not possible but that is hoped or wished for ▪ We would go if only we could—but unfortunately we can't. ▪ We would have gone if only we could have—but unfortunately we couldn't. ▪ I wish I could fly! = (formal) Would that I could fly! 3 — used in speech to make a polite request or suggestion ▪ Could you please pass me the salt? ▪ Could [=can] I leave a little early today? ▪ If you could come early, we would be pleased. ▪ “Could I do it tomorrow instead of today?” “Yes, you can.” ▪ Could I get you a cup of coffee? [=do you want a cup of coffee?] ▪ If tape doesn't work, you could try glue. ▪ “Where can I stay?” “Well, you could always stay with me.” 4 — used to say that you are annoyed by something that was or was not done ▪ He could have at least paid for dessert! ▪ Why are you always late? You could try being on time for once! ▪ If she wasn't going to make it, she could have called. ▪ You could at least tell me why you were late! 5 — used in statements that express a strong emotional reaction ▪ I could have died of embarrassment! [=I was very embarrassed] ▪ I could just kill him! [=I am very angry at him] ▪ When she told me I'd won, I could almost have hugged her! [=I felt like hugging her] ▪ I'm so frustrated I could scream! [=I feel like screaming] 6 — used in statements that describe something as very bad, good, etc. ▪ What could be better than this? ▪ Registering could not be simpler. [=registering is very simple] ▪ I could hardly be more pleased [=I'm very pleased] with the way things are going. ▪ The situation couldn't be worse/better. [=the situation is as bad/good as it can be] ▪ I couldn't be happier [=I'm very happy] with the way our new kitchen looks.
b — used with have to say that something was possible but did not actually happen ▪ You could have been seriously hurt. ▪ The accident could have been worse. ▪ The movie could have been better. [=the movie wasn't very good] ▪ They could have succeeded if they had worked harder. ▪ The error could have lost the game for them. ▪ We could just as easily have fixed the engine ourselves.
c — used to talk about something that is not possible but that is hoped or wished for ▪ We would go if only we could—but unfortunately we can't. ▪ We would have gone if only we could have—but unfortunately we couldn't. ▪ I wish I could fly! = (formal) Would that I could fly!
could care less — see 2care
could do with
◊If you could do with something, you need it or would be helped by getting or having it.
▪ Is there a restaurant nearby? I could do with something to eat. ▪ This room could do with a fresh coat of paint.
▪ Is there a restaurant nearby? I could do with something to eat. ▪ This room could do with a fresh coat of paint.
