Source : Webster's Revised Unabridged Dictionary (1913)

Fantastically \Fan*tas"tic*al*ly\, adv.
   In a fantastic manner.

         the letter A, in scarlet, fantastically embroidered
         with gold thread, upon her bosom.        --Hawthorne.

Source : WordNet®

fantastically
     adv : in a fabulous manner; "she was a fabulously gifted player"
           [syn: {fabulously}]