Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
PACY
As described in historical dictionaries
Patronymica Britannica (1860)
PACY. Either from Paci, near Evreux, (latinized in charters Paceium) or from Pace near Alengon, both in Normandy.