GAHARIET.  Arthurian legend name of a knight, brother to Gawain, Agravain, and Gareth.  Rhys states that this name can be traced back to Galiauet, which he believes to be a form of Welsh Gwalchaved (q.v.), meaning "hawk of summer."

... Gawain, singling out a chief named Choas, of gigantic size, began the battle by splitting him from the crown of the head to the breast.  Galachin encountered King Sanagran, who was also very huge, and cut off his head.  Agrivain and Gahariet also performed prodigies of valor.  Thus they kept the great army of assailants at bay,... (Mythology, Bulfinch, 1913)

    As to the name Gahariet, we may remark that the Huth Merlin gives Gauvain two brothers, called respectively Gahariès and Guerrehès, and they appear in Malory as Gareth and Gaherys.  In point of fact, however, they seem to be variants of a single name best represented by Gaharies in the nominative and Gahariet in the other cases.  Now Gahariet admits of being traced back through easy stages of misreading or miscopying to Galiauet, (which must be a form of Gwalchavet or Gwalchaved), namely, by reading li into h, a mistake very easily committed in the manuscripts... (Studies in the Arthurian Legend, Rhys, 1891)