Written records of cop date back to the mid-1800s. That's when the term first appeared on the crime scene as a shortened form of copper, another name for one who nabs criminals. Both cop and copper seemed likely suspects for interesting word origins, and it wasn't long before theories on their derivations began to hit the streets.

Cop, it was said, stood for Constable on Patrol, or maybe Chief of Police. No, said another acronym aficionado: it represents Custodian of Peace. Someone who preferred eponyms to acronyms claimed that cop came from the surname of a notable police chief.

Not satisfied we've broken the case? Try on these clothing theories for size. Police officers were said to have donned copper helmets in an effort to protect their heads from heavy objects. Or maybe it was copper-toed shoes. A group of theories variously pointed to (take your pick) large copper buttons, copper stars, or copper shields.

But etymologists (whose work it is to collar suspicious word origins) make a different case. They allege the nouns cop and copper come from the verb cop, an old slang word that describes what police do to criminals — that is, catch them. The verb form itself, say the word sleuths, may have stolen into English from Dutch around the year 1700.