What's the origin

[Gonpostal]

Why do they call a police officer a "COP"?

[gen2]

probably from "Constable on patrol"

[Quizmonkey]

Don't agree! 'To cop' means to capture or arrest so one who arrests is a copper, later abbreviated to cop.

[Gonpostal]

While the first answer sounds plausable, I think I'd heard that COP was shortened from copper but I thought it had something to do with their uniform maybe?  Maybe copper buttons or something?

[Quizmonster]

'Cop' is an old English word meaning 'to catch'. It comes from the French verb 'caper' and, even further back, from the Latin one 'capere'. That's what a policeman's job is...to catch baddies. Hence the name. Lots of people say it comes from the copper buttons they supposedly had on their uniforms long ago and others say it is an acronym for 'Constable on Patrol'. However, I'd advise you to go with the etymology offered by the word-bible...The Oxford English Dictionary. It says cop = catch is the explanation, as Quizmonkey suggests.

[Quizmonkey]

Thanks Monster - gen2's suggestion reminds me of that other myth: that a certain word comes from the hastily scribbled acronym when old lawmen were writing up charge-sheets: for unlawful carnal knowledge...

[Quizmonster]

Yes, Quiz, that's one of my favourite bits of folk etymology, too. I call this sort of thing 'acronymania'.

[Grunty]

Can't be sure, but it is believed to be from Sir Robert Peel, the Home Secretary when the police were introduced.  He was red haired and was known as "Copper".  For the same reason they became known as Peelers and Bobbies.