Word of the month: Piston

In this new regular column Anthony Pouton-Smith explores the obscure origins of everyday engineering words

When it comes to engineering the piston is one of the fundamental parts of an engine. At the time of the Industrial Revolution the piston carried the water away when it performed as a pump. Today we mostly associated the piston with the internal combustion engine but just how did it get its name?

The first known use in English dates from 1704. This is a Middle French word, where piston described ‘a large pestle’. Today the pestle, which always comes with a mortar, is found in kitchens and is used for grinding up herbs and spices. Traditionally chemists used same when grinding up ingredients for medicines. Yet working back deeper into history we find the Old Italian pistone which, a variant of pestone, came from pestare. Earlier still in Latin we find pistare and pistus all mean ‘to pound’, essentially what is being done with the pestle. 

Interesting to note that ‘piston’ has come into use for it could just as easily have been ‘embolus’. Seen a little earlier (1660) it is derived from the Latin embolus or ‘piston of a pump’, and ultimately from the Greek embolus ‘peg, stopper’ and a line which has given us the medical term ‘embolism’ when referring to an arterial blockage.