E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
In chess, the French call the bishop fou, and used to represent the piece in a fools dress; hence, Regnier says, Les fous sont aux échecs les plus proches des Rois (14 Sat.). Fou is a corruption of the Eastern word Fol (an elephant), as Thomas Hyde remarks in his Ludis Orientalibus (i. 4), and on old boards the places occupied by our bishops were occupied by elephants.
A Tom Fool. A person who makes himself ridiculous. (See TOM.)
The ancient and noble family of Tom Fool.Quarterly Review.