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
Diamond dust, tapioca snow, and sugar icebergs — a 1955 glossary of arctic and subarctic terms describes the environment in ways that sound poetic. And a mom says her son is dating someone who’s non-binary. She supports their relationship, but...
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...
“Sniffer” also occurs in industry for a similar instrument used in leak detection. It’s often modified: “helium sniffer,” etc.