Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
CLOSSON
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
(origin: Dutch.) The son of Klaas, the abbreviation of Nicholas among the Dutch. Klaas-son, the son of Nicholas. So Santa Klaas for St. Nicholas.