Dictionary.com
Thesaurus.com

silent alarm

American  

noun

  1. an alarm that alerts security personnel or the police without the knowledge of the intruder or criminal whose presence triggers it.

    The silent alarm set off a flashing light at the police station.

  2. any visual rather than audible alarm.

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Twice the operation was interrupted by police officers who came to Sinay’s office when she accidentally set off a silent alarm, but for the most part the copying proceeded without mishap.

From Los Angeles Times • Jun. 16, 2023

Police contacted Ms Leonard after a priority 999 call from a silent alarm system in her home had been logged.

From BBC • Jun. 5, 2023

China’s nosedive in childbearing is a silent alarm.

From Washington Post • Feb. 28, 2023

There’s also a silent alarm that vibrates to wake up one partner without disturbing the other.

From The Verge • Aug. 5, 2022

“Oh, God, Fern, it’s just you. The silent alarm went off, and I— What are you doing in here?”

From "The Wrong Way Home" by Kate O’Shaughnessy

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.