Short form of James, already recorded as early as the Middle Ages and now also used independently. Well-known bearers of the name have included the Scottish racing driver Jim Clark (1936–68), the British comedian Jim Davidson (b. 1953), and the Canadian actor Jim Carrey (b. 1962).
English: patronymic from an old personal name, either Old English Sigegār, Old Norse Sigarr, Old Danish and Swedish Sighar, or the Continental Germanic Sigger, all composed of related elements meaning ‘victory’ + ‘spear’.