tripwire

[trip-wahyuh r]

noun

a wire used to set off concealed explosives, as one stretched across a footpath to be struck and activated by the foot of an enemy soldier.

a wire that activates a trap, camera, or other device when stepped on, tripped on, or otherwise disturbed.

Origin of tripwire

trip¹ + wire

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for tripwire

Contemporary Examples of tripwire

The tripwire for an unfolding plot to take control of the flight would be the transponder, operated by a switch beside the pilots.
Who Gagged the Search for MH370?
Clive Irving
June 22, 2014
The transponder is really the tripwire for whatever began to unfold on that jet.
The Tripwire on Flight 370
Clive Irving
March 17, 2014
The emotions of Democrats are on a tripwire, ready to react at the slightest provocation.
Is Hillary Ditching Senate Dems?
Eleanor Clift
February 11, 2014

British Dictionary definitions for tripwire

tripwire

noun

a wire that activates a trap, mine, etc, when tripped over

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012