to say that you are annoyed, unhappy or not satisfied about somebody/something complain (to somebody) (about/of something) I'm going to complain to the manager about this. The defendant complained of intimidation during the investigation. She never complains, but she's obviously exhausted. (informal) ‘How are you?’ ‘Oh, I can't complain (= I'm all right).’ complain (that)… He complained bitterly that he had been unfairly treated. + speech ‘It's not fair,’ she complained.