v. phr. 1a. slang To hit hard. He drew back his fist and let the man have it. Give him a kick in the pants; let him have it!
Synonym: GIVE IT TO. 1b. slang To use a weapon on; to shoot or knife. The guard pulled his gun and let the robber have it in the leg.
Compare: OPEN UP. 1c. or let one have it with both barrels slang To attack with words; scold; criticize. Mary kept talking in class until the teacher became angry and let her have it.
Synonym: LIGHT INTO 2 . 2. informal To tell about it. Used in the imperative phrase, "let's have it". Now, Mary, let's have it from the beginning. We will take turns reading; John, let's have it from page one.