Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
SLADE
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
(origin: Local) A long flat piece or slip of ground between hills.
Patronymica Britannica (1860)
SLADE. This word has been variously defined as a vallej', a hollow, a den, a hanging wood, a plain, a breadth of green land in fields and plantations, &c. See Eng. Siirn. i. 83. The form of the surname in H.R. is De la Slade.
Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
Surname type: Location or geographical feature
Origin: English
Region of origin: British Isles
Country of origin: England
Religion of origin: Christian
Language of origin: English