pistone

Pistone is Italian for a large pestle, from pestare (to pound, to crush), from Latin pistare (to pound). The earliest pistons were simple plungers — rods pushed into cylinders to compress air or move fluid. The resemblance to a pestle in a mortar is direct: a rounded object pushed into a hollow tube. The word came from the kitchen to the workshop.

The piston became a critical component of the steam engine. Thomas Newcomen's atmospheric engine of 1712 used a piston in a cylinder — steam pressure pushed the piston up, and atmospheric pressure pushed it down when the steam condensed. James Watt improved the design in the 1760s with a separate condenser, making the piston engine efficient enough to power the Industrial Revolution. The piston was the heart of the machine.

Internal combustion engines, developed in the late nineteenth century, use pistons driven by exploding fuel-air mixtures. Nikolaus Otto's four-stroke engine (1876) established the cycle that every gasoline car engine still uses: intake, compression, combustion, exhaust. Each stroke moves the piston up or down in the cylinder. A typical car engine fires its pistons thousands of times per minute.

The word 'piston' also names a component of brass instruments. A piston valve, used in trumpets and tubas, is a plunger that redirects air through different lengths of tubing to change pitch. The musical piston and the mechanical piston share the same design: a close-fitting rod inside a cylinder. The Italian pestle is in both.