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).
Irish: variant of Dermond, a reduced Anglicized form of Gaelic Ó Duibhdhiorma ‘descendant of Duibhdhiorma’ a personal name meaning ‘black trooper’ (see Dormer 3). There has been some confusion between the personal names Duibhdhiorma and Diarmaid, so that Dearmond alternates with McDermott.