cold-case

The term "cold-case" is a modern compound noun originating in mid-20th century American police jargon. It combines the adjective "cold," which metaphorically extends its core meaning of low temperature to signify something that has lost warmth, activity, or recent leads, with the noun "case," derived from the Latin casus (a fall or occurrence), which evolved to denote a specific instance requiring investigation. The logic is vividly metaphorical: an unsolved investigation grows "cold" over time as evidence trails fade, witnesses become unavailable, and active investigative work ceases, much like a physical object loses heat. This compound effectively captures the stalled, dormant status of such long-unsolved files within law enforcement.

Structure: cold (adjective) + case (noun) - cold: From Old English cald/ceald, of Germanic origin; related to Dutch koud and German kalt. Functions as an adjective describing low temperature, here used metaphorically to indicate inactivity or lack of recent progress. - case: From Old French cas, from Latin casus (a fall, chance, occurrence), from the verb cadere (to fall). Functions as a noun meaning an instance of a particular situation or a matter under investigation, especially by police.