Lord is a deferential appellation for a person or deity who has authority, control, or power over others; a master, chief, or ruler. In only a few cases is "lord" a substantive title in itself, most commonly that of the Lord of the Manor and certain vestigial titles from the age of feudalism such as Lord of Mann, in other cases it is a generic term applied, for example, to persons who hold a title of the peerage (a legal system of largely hereditary titles in the United Kingdom, which constitute the ranks of British nobility and is part of the British honours system; the holder of a peerage is termed a peer) or persons entitled to courtesy titles, or to refer to a group or body of peers.
Under the feudal system, lord has a wide, loose and varied meaning. An overlord was the person from whom a landholding or a manor was held by a mesne lord or vassal under various forms of feudal land tenure. The modern term "landlord" is a vestigial survival of this function. A liege lord was a person to whom a vassal owed sworn allegiance. Neither of these terms were titular dignities, rather factual appellations, which described the relationships of two persons within the highly stratified feudal social system. For example, a man might be lord of the manor to his own tenants but a vassal to his own overlord, who in turn was a vassal to the king. Where a knight was a lord of the manor, as was generally the case, he is referred to in contemporary documents as "John (Surname), knight, lord of (manor name)". A feudal baron was a true titular dignity, with the right originally to attend Parliament, yet even a feudal baron, lord of the manor of many manors, was a vassal to the king.