Wikipedia says this name means:The name Mordred (found as Modredus in Geoffrey of Monmouth's Historia Regum Britanniae) comes from Old Welsh Medraut (comparable to Old Cornish Modred and Old Breton Modrot) and is ultimately derived from Latin Moderātus meaning "within bounds, observing moderation, moderate". [noted -ed]Sources: Cane, Meredith. Personal Names of Men in Wales, Cornwall and Brittany 400-1400 AD, University of Wales Ph.D. thesis, 2003, pp. 273-4.Lewis, Charlton, T., An Elementary Latin Dictionary, New York, Cincinnati, and Chicago. American Book Company. 1890.Wiktionary - under descendants of Moderatus: https://en.wiktionary.org/wiki/Moderatus
The name Mordred (found as Modredus in Geoffrey of Monmouth's Historia Regum Britanniae) comes from Old Welsh Medraut (comparable to Old Cornish Modred and Old Breton Modrot) and is ultimately derived from Latin Moderātus meaning "within bounds, observing moderation, moderate". [noted -ed]
Sources:
Cane, Meredith. Personal Names of Men in Wales, Cornwall and Brittany 400-1400 AD, University of Wales Ph.D. thesis, 2003, pp. 273-4.
Lewis, Charlton, T., An Elementary Latin Dictionary, New York, Cincinnati, and Chicago. American Book Company. 1890.
Wiktionary - under descendants of Moderatus:
https://en.wiktionary.org/wiki/Moderatus