elder son of Adam and Eve, the first murderer and the first fratricide, from Hebrew Qayin, literally "created one," also "smith," from Semitic stem q-y-n "to form, to fashion." Figurative use for "murderer, fratricide" is from late 14c. The Cainites were a 2c. heretical sect who revered Cain, Judas, and other wicked characters in Scripture.
To raise Cain is first recorded 1840. Surnames McCain, McCann, etc., are a contraction of Irish Mac Cathan "son of Cathan," from Celtic cathan, literally "warrior," from cath "battle."