v. , informal 1. To hide something wrong or bad from attention. The spy covered up his picture-taking by pretending to be just a tourist. A crooked banker tried to cover up his stealing some of the bank's money by starting a fire to destroy the records.
Compare: COVER ONE'S TRACKS 2 . 2. In boxing: To guard your head and body with your gloves, arms, and shoulders. Jimmy's father told him to cover up and protect his chin when he boxed. 3. To protect someone else from blame or punishment; protect someone with a lie or alibi. Often used with "for". The teacher wanted to know who broke the window and told the boys not to try to cover up for anyone. The burglar's friend covered up for him by saying that he was at his home when the robbery occurred.