Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
CRADOCK
As described in historical dictionaries
Patronymica Britannica (1860)
CRADOCK. Welsh, Cradoc, latinized Caractacus — illustrious in British history from the patriotic opposition of the Silurian leader, Caractacus, to the forces of the Roman emperor Claudius.