1. a shot or pass made with the head: "two minutes later O'Brien had a header cleared off the line by Kennedy"
2. a headlong fall or dive.informal
3. a brick or stone laid at right angles to the face of a wall.
4. a line or block of text appearing at the top of each page of a book or document.
▪ the part of an email before the message, containing information such as the subject and sender. "every email message needs a header indicating the sender's identity and address"
5. a raised tank of water maintaining pressure in a plumbing system.
6. a person who ropes a steer by its head (as opposed to its heels), especially in a team-roping rodeo event:North American"the steer ran straight and the header made a good catch"