1 a device in a pipe or tube which controls the flow of air, liquid or gas, letting it move in one direction only 活门，阀（管道中控制空气、液体或气体流动的机械装置，使其只朝一个方向流动）: a radiator valve 散热器活门the valve on a bicycle tyre 自行车轮胎的气门 ☞picture at bicycle 见bicycle插图

2 a structure in your heart or in a VEIN(= a tube that carries blood to the heart)that lets blood flow in one direction only （心脏或静脉的）瓣，瓣膜 ☞picture at heart 见heart插图