Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
LACY
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
(origin: Local) Derived from a place in France by that name. Sire De Lacy came into England with William the Conqueror. The Lacys afterward settled in Ireland.
Patronymica Britannica (1860)
LACY. Roger de Laci, eldest son of Walter de L., came over with William the Conqueror, and was rewarded with the tenure in capite of IIG lordships. To Ilbert de Laci the Conqueror gave the castle and town of Pontefract, co. York,
Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
Origin: English
Region of origin: British Isles
Country of origin: England
Religion of origin: Christian
Language of origin: English