Modern coinage, most common in North America. It is of unknown origin, probably a fanciful coinage based on Marlene or Charlene, or both. It became famous in the 1950s as the name of the American actress and beauty columnist Arlene Dahl (b. 1924).
Irish: Anglicized form of Gaelic Ó Manacháin ‘descendant of Manachán’, a personal name representing a diminutive of manach ‘monk’. See also Monk. The Gaelic name is sometimes interpreted as if it were Ó Muineacháin ‘descendant of the little shrubbery’, and is sometimes translated as Thornton. Compare the place name Monaghan.