cop-killer

Etymology 1
From.

Noun

 * 1) A person who deliberately kills an on-duty police officer.

Etymology 2
From the bullet's (bullets') supposed ability to penetrate body armor, thus endangering police officers.

Noun

 * 1)  A Teflon-coated bullet.

Usage notes

 * First used by gun control advocates in the early 1980s following an NBC show on the subject.

Translations

 * Spanish: matapolicías