fiendishly

Meanings

1. 1
   adv

   In a fiendish manner; evilly, wickedly.

   At a side door, reclined on a couch, two guards of the haram, with their naked swords grasped in their hands, and features, fiendishly contorted between sleep and dissolution, seemed to menace death to any who should venture to approach.

2. 2
   adv

   Extremely, very in harsh or negative contexts.

   Either the Russians are so fiendishly clever that they've managed to keep one of their agents running in this organization for over twenty years or they're so fiendishly clever that they're sending us false defectors to claim that they have.

3. 3
   adv

   as a devil

Etymology

From fiendish + -ly.