tripwire
noun [ C ] uk/ˈtrɪp.waɪər/ us/ˈtrɪp.waɪr/
(爆炸装置、枪炮的)引爆线,拉发线;(捕兽装置的)绊索,绊网
a wire stretched low above the ground that operates an explosive device, a gun, or a device for catching animals when it is touched by the foot of a person or animal