Martin Luther has carefully chosen the form of his last name. His family was of Low German descent and had the name Luder with a lot of variations (Lüder, Luder, Loder, Ludher, Lotter, Lutter, or Lauther). Martin Luther selected the spelling of his last name to honor Duke Leuthari II. (7th century) and to derive it from Greek eleutheros "free". He used for some time the name Eleutherios.