GUINGAMOR.  Breton Arthurian name, probably meaning "greatly fair."

... The prose romances supply us with... only scattered allusions to Guiomar, all of which represent him as among the favored and gallant knights of Arthur.   To answer our question we must in the first place recall the experiences of the hero, Guingamor, celebrated in Breton lays.  His name Zimmer regards as a development of Guigomar.  The change of the termination -omar to -amor, -amuer, Zimmer explains as the result of a confusion between -omar and the common Breton termination -mor, -mer, -muer, which means great; and the Guin- for Gui- in the first member as developed by analogy with the many Breton names in which Guin-, Guen- forms the first syllable.  This merely indicates that the forms Guingamor, Guingamuer are transparent, and even if not connected phonologically with Guigomar might by popular usage easily arise from it... (Studies in the Fairy Mythology of Arthurian Romance, Paton, 1903).