Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
GREGOR
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
(origin: Gaelic.) From Greigh a herd (Latin Grex), and fear a man, a herdsman. In the Cornish British Gryger or Gruger signifies a partridge.
Patronymica Britannica (1860)
MAC GREGOR. This clan Is deduced from Gregor, or Gregorius, 3rd son of Alpin, a Scottish monarch of the VIII. cent., who was named after his godfather, Pope Gregory IV. It is often modified to Greer and Greerson,
Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
Surname type: From given name or forename
Origin: Celtic
Region of origin: British Isles
Country of origin: Scotland
Religion of origin: Christian
Language of origin: Gaelic