blue canary
n.— «As miners once used caged canaries to warn them of poisonous gas underground, the greatest fear of these two streetwise veterans is a “blue canary,” a police officer or emergency worker who unknowingly walks into his or her demise.» —“Homeland Security In St. Louis” by Phillip O’Connor St. Louis Post-Dispatch (Missouri) Mar. 23, 2003. (source: Double-Tongued Dictionary)
Further reading
Asthenosphere, a geologist’s term for the molten layer beneath the earth’s crust, sparks a journey that stretches all the way from ancient Greece to the author of Uncle Tom’s Cabin. Plus: What the heck is a dogberg? It’s when...
The adjectives canine and feline refer to dogs and cats. But how does English address other groups of animals? Plus, cabin fever has been around much longer than the current pandemic. That restless, antsy, stir-crazy feeling goes back to the days...