Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
GRUNDY
As described in historical dictionaries
Patronymica Britannica (1860)
GRUNDY. Apparently the old Teutonic personal name Grund, whence Grundisborough, a parish in Suffolk.
Origin: English
Region of origin: British Isles
Country of origin: England
Religion of origin: Christian
Language of origin: English