Source : Webster's Revised Unabridged Dictionary (1913)

Preternaturally \Pre`ter*nat"u*ral*ly\ (?; 135), adv.
   In a preternatural manner or degree. --Bacon.

Source : WordNet®

preternaturally
     adv : in a supernatural manner; "she was preternaturally
           beautiful" [syn: {supernaturally}]