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