Gasket

For example, in a motor car engine, the engine has cylinders that pump up and down. There's the cylinder head, which sits on top of the main body of the engine, which houses the pistons. Between these two big pieces of metal, is a thin gasket made out of something like graphite. If you just bolted the two bits together, air would leak out in between the gaps since the casting process is not perfect, and there would not be enough compression in the engine, which would cause it to lose power.

Gas"ket (?), n. [Cf. F. garcette, It. gaschetta, Sp. cajeta caburn, garceta reef point.]

1. Naut.

A line or band used to lash a furled sail securely. Sea gaskets are common lines; harbor gaskets are plaited and decorated lines or bands. Called also casket.

2. Mech. (a)

The plaited hemp used for packing a piston, as of the steam engine and its pumps.

Any ring or washer of packing.

© Webster 1913.