earlier Tom foole, from Tom, shortened form of Thomas, a proper name + foolefool entry 1
Note: The word was perhaps originally an appellation for a jester. The account rolls of Durham Abbey record disbursements made for a certain Thome Fole (also in Latin as Thomas Fatuus), presumably the name of a professional jester, for items of dress in the 1330's and for his funeral during the period 1356-57 (see Oxford English Dictionary, first edition, and Middle English Dictionary s.v. Tomme).