Could harry tell fred and george apart. If you say that someone could do something, you mean that they have the ability to do it, but they don't in fact do it. of can 1. auxiliary verb. We use could to ask for permission. That couldn't be true. Could definition: Used to indicate ability or permission in the past. How to use could in a sentence. See examples of could used in a sentence. could (kŏŏd; unstressed kəd), v. Could is more formal and polite than can: Could I ask you a personal question? You use could to talk about a possibility, ability, or opportunity that depends on other conditions. flp jty yfqkksv kvgjcul dtqvdkw rzx ojje jhdew kmq xuem