(archaic) simple past tense and past participle of can

Eye dialect spelling of could have or could've. / Misconstruction of could have or could've.

simple past tense of can / Used as a past subjunctive (contrary to fact). / Used to politely ask for permission to do something. / Used to politely ask for someone else to do something.

Something that could happen, or could be the case, under different circumstances; a potentiality.

plural of could

To need something that would be beneficial.

(double modal / stacked modal, used in some dialects, chiefly Southern US) might be able to (used to soften "could" or make it even more conditional)

simple past tense of could do with / simple past tense of can do with

(informal) Is very sure about; especially when the thing in question is apparently not the case or could be doubted.

(idiomatic) Used to denote a location with an interesting or controversial history.