piston
UK[ˈpɪstən]US[ˈpɪstən]
n
a short solid cylinder that fits inside a tube in an engine and moves up and down to make other parts of the engine move.
Etymology
the word 'piston' entered english in the early 18th century from french, where it meant 'pestle'. the french term derived from italian 'pistone', a variant of 'pestone', meaning 'large pestle', which itself came from 'pestare' – 'to pound'. this italian verb finds its origin in the late latin 'pistare', a frequentative form of 'pinsere', meaning 'to pound or crush'. the mechanical sense of the word, referring to the sliding component in an engine, developed from the analogy of its pounding or thrusting motion within a cylinder, much like a pestle moves within a mortar.
Analysis
this word is a simplex loanword from french. it does not contain separable morphemes in its modern english spelling.
Examples
the engine's power depends on the smooth movement of the piston within the cylinder.
a faulty piston ring can cause the engine to burn oil and lose compression.
the mechanic replaced the worn piston and connecting rod.