FELICITATE is a 10 letter word that starts with F.

1. \Fe*lic"i*tate\, a. [L. felicitatus, p. p. of
   felicitare to felicitate, fr. felix, -icis, happy. See
   {felicity}.]
   Made very happy. [Archaic]
   
         I am alone felicitate In your dear highness' love.
                                                  --Shak.
   
   

2. \Fe*lic"i*tate\, v. t. [imp. & p. p. {Felicitated};
   p. pr. & vb. n. {felicitating}.] [Cf. F. f['e]liciter.]
   1. To make very happy; to delight.
   
            What a glorious entertainment and pleasure would
            fill and felicitate his spirit.       --I. Watts.
   
   2. To express joy or pleasure to; to wish felicity to; to
      call or consider (one's self) happy; to congratulate.
   
            Every true heart must felicitate itself that its lot
            is cast in this kingdom.              --W. Howitt.
   
   Syn: See {Congratulate}.