Elaboration of Mary, with the addition of the productive suffix -lyn (see Lynn). It is recorded in the 18th century, possibly as a blend of Mary and Ellen, but first came into regular use in the 20th century, peaking in the 1940s and 50s. Since then its use has been surprisingly moderate, considering the enduring popularity of the film star Marilyn Monroe (1926–62), baptized Norma Jeane Baker.
Scottish, Irish, and English: nickname for an unbridled and licentious man, from Middle English laghless, lawelas (a compound of late Old English lagu ‘law’ (from Old Norse) + the native suffix -l(ē)as ‘without’, ‘lacking’). Reaney suggests additionally that this name may have referred to an outlaw (i.e. one from whom the protection of the law had been withdrawn), but this seems unlikely.