Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
MERCY
As described in historical dictionaries
Patronymica Britannica (1860)
MERCY. Perhaps applied to a person who had performed this character iu some m}'stery or miracle-play. Or it may be the same as Marcey.
Origin: English
Region of origin: British Isles
Country of origin: England
Religion of origin: Christian
Language of origin: English