piston

Meanings

1. 1
   noun

   a solid disk or cylinder that moves tightly inside a larger cylinder to transmit pressure or drive a machine

   Steam forced the piston upward inside the engine's cylinder.

2. 2
   noun

   a movable valve on a brass instrument that changes the length of its air path and therefore its pitch

   The trumpeter pressed the second piston to change the note.

Borrowed from French piston, from Italian pistone ('large pestle'), related to pestare ('to pound or crush'). The mechanical part was named for its pestle-like plunging motion.

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