Meaning

noun a murderer (especially one who kills a prominent political figure) who kills by a surprise attack and often is hired to do the deed

noun a member of a secret order of Muslims (founded in the 12th century) who terrorized and killed Christian Crusaders

originFrom either French assassin or Italian assassino, from Arabic أَسَاسِيِّين (ʔasāsiyyīn, “people who are faithful to the foundation [of the faith]”) and the folkloric etymology Arabic حَشَّاشِين (ḥaššāšīn, “hashish users; low-lives”). The mathematical sense was introduced by Bourbaki, playing on the notation operatorname Ass(M) and the fact that an associated prime is the annihilator of an…

Etymology from Wiktionary, CC BY-SA 3.0