CARWIN

Origin and etymology In historic texts In the 1881 census Distribution map

As described in historical dictionaries

An Etymological Dictionary of Family and Christian Names (1857)

(origin: Cor. Br. Local) The white castle; from caer, a castle, and win or gwin, white.

Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.

BritishSurnames.uk is a Good Stuff website.