Original: The title may also be used in conjunction with others to denote a superior holder of an otherwise generic title, in such combinations as "Lord Mayor" or "Lord Chief Justice".
Simplified: The word actually comes from the Old English forms for "loaf" (bread) and "ward" (used to mean "protector", although today it means "one who is protected"). So a lord or "loaf ward" was originally "the one who protected the loaf".