Whence comes the name Greyhound?
Webster: From Old English grighund and/or Old Norse greyhundr, the latter prefix from Indoeuropean ghru-, variation of gher-, to shine, whence also gray.
In other words, Webster ignores grig- and simply describes the derivation of grey-.
But the meaning to shine brings to mind the Irish for sun, grian.
Oxford English Dictionary (OED): “The etymology of the first element is unknown; it has no connexion with grey or with grew, Greek, nor with grey = badger.”
The OED does note that the Old English grig- or grieg- is equal to the the Old norse grey-.
It also notes that the variant grifhound is from variant pronunciation of grewhound (grew- being a corruption of grey with the idea of the breed having a “Greek” origin, i.e., an association with the origins of human civilization).
But perhaps the prefix grif- stands on its own. In French a griffe is a claw, as derived from the Frankish grif. In German, griff is a noun for catch, and greif is a verb for grasp. All of these fit the greyhound.
Further possibilities are suggested in Irish. Gadhar (pronounced “geyer”) means hunting dog. Gaothar (“gih-her”) means like the wind. Gaobhar (“givver”) means near, which is applicable as the greyhound was the companion of chiefs and kings: The legendary warrior Fionn Mac Uail’s favorite dogs were the greyhounds Bran and Sceólan; the name of the other legendary warrior Cú Chulainn, whose mythical cycle is that of the sun (grian), actually means the greyhound (cú) of Culann.
Rather than pinned to any of these, the name, and the creature herself, would seem to contain them all.
Irish provides yet another possibility with the word for hare: giorria (“giriyeh”). The word is geàrr (“gyarr”) in Scottish, from gearr-fhiadh, meaning short deer, which is the same in Irish and also meaning hare. It is pronounced “g’arig”, which is essentially the Irish pronunciation of grig-. Since most hunting hounds take a name from their prey, this seems to suggest a likely derivation for greyhound.
And Webster says hare comes from the Indoeuropean root kas [or has (whence ashen)], meaning gray! However, the OED says it is not related to similar germanic words for gray.