柯林斯詞典piston /?p?st?n/ (pistons) 1. N-COUNT A piston is a cylinder or metal disc that is part of an engine. Pistons slide up and down inside tubes and cause various parts of the engine to move. 活塞 返回 piston劍橋詞典a short , solid piece of metal that moves up and down inside a cylinder in an engine to press the fuel into a small space and to send the power produced by it to the wheels （發(fā)動(dòng)機(jī)）活塞 返回 piston