assassin

noun

1. Someone who intentionally kills a person, especially a professional who kills a public or political figure.

   “The hand that held the bond of so many jarring interests lay powerless beneath the pall. The perils of war had been about him, and the midnight assassin had watched his path; yet he died quietly in his bed.”

   “What has violence ever accomplished? What has it ever created? No martyr's cause can ever be stilled by an assassin’s bullet.”

   “Even without hovering drones, a lurking assassin, a thumping score and a denouement, the real-life story of Edward Snowden, a rogue spy on the run, could be straight out of the cinema. But, as with Hollywood, the subplots and exotic locations may distract from the real message: America’s discomfort and its foes’ glee.”

2. Any ruthless killer.
3. (capitalized, historical, usually)A member of the Nizari Ismaili Muslim community of the Alamut Period.

   “The Assassines, a nation depending of Phœnicia, are esteemed among the Mahometists of a soveraigne devotion and puritie of maners; they hold, that the readiest and shortest way to gaine Paradise, is to kill some one of a contrary religion[…].”

4. (humorous)An associated prime of a module.

verb

1. (nonstandard)To assassinate.