WordNet (r) 3.0 (2006):

Lancelot
    n 1: (Arthurian legend) one of the knights of the Round Table;
         friend of King Arthur until (according to some versions of
         the legend) he became the lover of Arthur's wife Guinevere
         [syn: Lancelot, Sir Lancelot]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "Lancelot":
   Bayard, Don Quixote, Gawain, Ritter, Sidney, Sir Galahad, bachelor,
   banneret, baronet, caballero, cavalier, chevalier, companion,
   knight, knight bachelor, knight banneret, knight baronet,
   knight-errant