- a simple past tense of can1.
- (used to express possibility): I wonder who that could be at the door. That couldn't be true.
- (used to express conditional possibility or ability): You could do it if you tried.
- (used in making polite requests): Could you open the door for me, please?
- (used in asking for permission): Could I borrow your pen?
- (used in offering suggestions or advice): You could write and ask for more information. You could at least have called me.
- used as an auxiliary to make the past tense of can 1
- used as an auxiliary, esp in polite requests or in conditional sentences, to make the subjunctive mood of can 1 could I see you tonight?; she'd telephone if she could
- used as an auxiliary to indicate suggestion of a course of action
- used as an auxiliary to indicate a possibility
