Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
SOCKMAN
As described in historical dictionaries
Patronymica Britannica (1860)
SOCKMAN. The sochemun or socliemannus, so frequently occurring in Domesday, was an inferior land-owner, who had possessions in the solie or fi-anchise of a great baron. Nichols' Leicestersh. At Walcote, CO. Lincoln, a Sockman held his lands by the tenure of ploughing with two oxen. Ellis, Introd. Domesd.