trip wire

Thesaurus

Noun	1.	trip wire - a small military force that serves as a first line of defense; if they become engaged in hostilities it will trigger the intervention of stronger military forcesmilitary force, military group, military unit, force - a unit that is part of some military service; "he sent Caesar a force of six thousand men"armed forces, armed services, military, military machine, war machine - the military forces of a nation; "their military is the largest in the region"; "the military machine is the same one we faced in 1991 but now it is weaker"
	2.	trip wire - a wire stretched close to the ground that activates something (a trap or camera or weapon) when tripped overwire - ligament made of metal and used to fasten things or make cages or fences etc

Translations

filo teso che fa scattare una trappola