modal verb

could

Translation

could (past ability), could (possibility), could (request)

I could swim when I was five.

It could rain this afternoon.

Could you pass the salt, please?

could + ((base verb)) I could see the sea from my window.

Could + ((sb.)) + ((base verb))? Could you open the door?

Synonyms: might, may (for possibility); was able to (for past ability).

From Old English 'cūthe', past tense of 'cunnan' (to be able).

Think of 'could' as a 'softer' version of 'can', used for the past, possibilities, or politeness.