Source : Webster's Revised Unabridged Dictionary (1913)

Fon \Fon\, n. [Of Scand. origin; cf. Icel. f[=a]ni silly,
   f[=a]na to act silly, Sw. f[*a]ne fool. Cf. {Fond}, a.]
   A fool; an idiot. [Obs.] --Chaucer.