detector
n. countablen. a machine or tool that finds something that is hidden or hard to see. You use it to search for things like smoke, metal, or lies.
n. a device or instrument designed to identify the presence of a specific substance, signal, or physical phenomenon. Often functions as the second element in a compound noun phrase.
The smoke detector started beeping while I was cooking.
Security guards at the airport use a metal detector to check passengers for prohibited items before they board.
Modern research facilities utilize a highly sensitive particle detector to observe subatomic interactions that are otherwise invisible to the naked eye.
Borrowed from Latin dētēctor. Equals detect + -or (agent noun forming suffix).
Frequently used in compound nouns such as 'smoke detector', 'lie detector', or 'motion detector'.