Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
FARADAY
As described in historical dictionaries
Patronymica Britannica (1860)
FARADAY. This, like other compounds of (lay, is not very easily explained. Mr. Ferguson derives it from A-Sax. faro, a traveller, with dufj as a suffix ; this, however, assists us but little.