Probably a contracted form of Meriel, but also associated with the small class of girls' names derived from birds, since it is identical in form with Old French merle ‘blackbird’ (Latin merula). The name came to public notice in the 1930s with the actress Merle Oberon (1911–79, born Estelle Merle O'Brien Thompson).
English: topographic name for someone who lived by a hill or tumulus, Old English beorg, a cognate of Old High German berg ‘hill’, ‘mountain’ (see Berg). This name has become confused with derivatives of Old English burh ‘fort’ (see Burke). Reaney suggests a further derivation from Old English būr ‘bower’ + hūs ‘house’.