piston: [18] The Latin verb pinsere meant ‘beat, pound’. Its past participial stem pist- formed the basis for the noun pistillum ‘grinding stick, pestle’ (from which English gets pistil ‘female flower part’ [18], an allusion to its shape). This passed into Italian as pestello, from which English gets pestle [14]. From the Italian stem pest- was formed pestone ‘rammer’, whose variant pistone gave French piston – whence English piston. => pestle, pistil
piston (n.)
1704, from French piston, from Middle French piston "large pestle," from Old Italian pistone "a piston," variant of pestone "a pestle," from pestare "to pound," from Late Latin pistare, frequentative of Latin pinsere (past participle pistus) "to pound" (see pestle). As a verb from 1930.
