Complex sentence: Miller or Millar is a surname of English, Scottish origin, principally derived from the occupational name for a miller; or in the United States it may be derived from many cognate surnames from other European languages.
Split into simpler sentences: Miller or Millar is a surname of English, Scottish origin, principally derived from the occupational name for a miller. In the United States it may be derived from many cognate surnames from other European languages.