In network terminology, a header is a series of bytes with a well-defined structure that describe something about the bytes that follow it.

In C and numerous other programming languages a header or header file is a file referenced by other files. It typically defines constructs that are used in several places. By referencing the header, duplication can be avoided.

In automotive terminology, the first component of an exhaust system; the pipe that leads immediately off the manifold.

An important part of performance tuning consists of matching the header to the engine configuration and vice versa, because the header's geometry determines the flow of exhaust gases from the cylinder. The maximum throughput of a header helps determine how freely the engine can breathe, which directly affects maximum power.

At the same time the header has to supply a certain amount of back pressure or the exhaust valves will not cycle properly, causing power loss and/or valve damage.

A move in British football (or "soccer") where the player directs a falling football by hitting it with his head. Since the only rule about making contact with the ball is that it cannot be touched with the arms or hands (except by the goalkeeper), this is a commonly used move when a player is closely surrounded by members of the opposing team but needs to direct the ball to someone else. The cry of "On me head, son!" indicates that a player wants to head the ball.

It can't be good for the brain though, surely?

Head"er, n.

1.

One who, or that which, heads nails, rivets, etc., esp. a machine for heading.

2.

One who heads a movement, a party, or a mob; head; chief; leader.

[R.]

3. Arch. (a)

A brick or stone laid with its shorter face or head in the surface of the wall.

(b)

In framing, the piece of timber fitted between two trimmers, and supported by them, and carrying the ends of the tailpieces.

4.

A reaper for wheat, that cuts off the heads only.

5.

A fall or plunge headforemost, as while riding a bicycle, or in bathing; as, to take a header.

[Colloq.]

 

© Webster 1913.

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