plunger
noun [ C ] uk/ˈplʌn.dʒər/ us/ˈplʌn.dʒɚ/
（疏通管道的）搋子，装有把手的吸盘
a suction device consisting of a cup-shaped piece of rubber on the end of a stick, used to get rid of things that are blocking pipes
（装置的）活塞，柱塞
a part of a device that you push down into it
He pressed down the plunger of his cafetière. 他压下了咖啡壶的活塞。