Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
GILLIES
As described in historical dictionaries
Patronymica Britannica (1860)
GILLIES. Gael. Gille Jesa, the Servant or Follower of Jesus ; " a youth under the protection of Jesus." .Johnstoue'.s Anecd. of Olave the Black. 1780.
Surname type: Diminutive
Origin: Celtic
Region of origin: British Isles
Country of origin: Scotland
Religion of origin: Christian
Language of origin: Gaelic