FERULE is a 6 letter word that starts with F.

1. \Fer"ule\ (? or ?; 277), n. [L. ferula: cf. F. f['e]rule.
   See {Ferula}.]
   A flat piece of wood, used for striking, children, esp. on
   the hand, in punishment.
   
   

2. \Fer"ule\, v. t. [imp. & p. p. {Feruled}; p. pr. & vb. n.
   {Feruling}.]
   To punish with a ferule.