header Definition

1. colloq
A fall or dive forwards.
2. football.
The hitting of the ball with the head.
3. building.
A brick or stone laid across a wall so that the shorter side shows on the wall surface. Compare stretcher.
4. A heading for a chapter, article, etc.
5a. A machine that removes the heads from castings, etc, or supplies heads, eg to wire to make nails;
5b. Someone who operates such a machine.
6. computing.
An optional piece of coded information preceding a collection of data, giving details about the data.
7. marketing.
A card attached to the top of a dumpbin giving information on the books displayed.
8. A reservoir that maintains a gravity feed or a static fluid pressure in an apparatus.

Form: header tank (also)