piston

Everyday

1. A piston is a short solid cylinder that moves up and down or in and out inside a tube, pushed by pressure; it is a key part of engines and pumps. tree →
2. (informal) «Like pistons» describes something moving fast up and down, like legs running. tree →

In the lessons

In science and D&T (design and technology) lessons, pistons show how pressure and force make movement: in car engines, burning fuel pushes pistons, which turn the wheels; in syringes and bike pumps, a piston pushes air or liquid. Children make simple hydraulic models with syringes.

Examples

• The piston moves up and down inside the engine. tree →
• A bike pump has a piston inside. tree →
• Pistons turn the crankshaft in a car. tree →
• We made a moving arm with syringes as pistons. tree →
• Steam pushed the pistons of the old train. tree →
• His legs went like pistons as he raced to the finish. tree →
• A syringe is a simple piston and cylinder. tree →
• The huge limbs moved as steadily as pistons, eight feet to each stride, and the wrinkled skin of the elbow points rustled. tree →

Note

Countable: pistons. Not to be confused with «pistol» (a gun). Pronounced «PISS-tun».