(origin: Welsh.) Derived from the castle of Carrw, in Wales. The castle by the water, from Caer, castle or fort, and ew, water.

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

CAREW. The Carews of Wales, Cornwall, &c., are descended from Gerald de Carrio, called by Giraldus Cambrensis (his relative) Gerald de Windsor and Fitz-Walter, who was castellan of Pembroke castle under Arnulf de Montgomery. He married Nest, a concubine of King Henry I., and had two sons; William Fitzgerald, the progenitor of the Carews, and Maurice who accompanied Strongbow into Ireland, and founded the FitzGeralds, Geraldines, and Geralds of that country. Gent. Mag., May, 1829. Carew castle is near Milford Haven. Carey is said to be another form of this name, which circ. 1300 was spelt De Carru.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.