verb

could

Used to express past ability, possibility, or a polite request.

I wonder if you could help me move this table.

Etymology

Old English cunnan connected knowing with ability. Could developed as the past form of can, with that distance also serving hypothetical possibilities and less direct, polite requests.

More examples

When I was younger, I could run for miles.
The roads could be icy tonight.
Could you please close the window?

Forms

could

Similar words

can: Expresses present ability rather than ability in the past.
might: Expresses possibility, but does not normally express ability or requests.