sniffer
n.— «As they talk, the flashlight—this is no ordinary flashlight—is on the job. It is a little-known device that surreptitiously traps a sample of a motorist’s breath and tests for the presence of alcohol. Commonly called “sniffers,” they are used by some law enforcement agencies in the central San Joaquin Valley.» —“Sniffing out crime” by Tim Eberly Fresno Bee (California) Dec. 31, 2006. (source: Double-Tongued Dictionary)
Further reading
Imagine telling someone how to get to your home, but without using the name of your street, or any other street within ten miles. Could you do it? We take street names for granted, but these words are useful for far more, like applying for a job or...
A listener named Tami contacted the show by WhatsApp to say that whenever someone would be talking about a subject that nobody else knew anything about, her father-in-law would respond with I had one of those, but the wheels came off. This is part...
“Sniffer” also occurs in industry for a similar instrument used in leak detection. It’s often modified: “helium sniffer,” etc.