function
She attended a charity function and made a generous donation.
The word event could be substituted for function and the meaning of the sentence would not change,
Flexible
fool
Forceless or Failing
The word is fantasy.
fatal
fetch
fax
Flicker.
foolproof
friction
Friable means easily crumbled or broken.
"Flamboyant" is a fun word to say that means elaborate. "Flashy" is a simpler word that means the same thing.