Fell

1. Of a strong and cruel nature; eager and unsparing; grim; fierce; ruthless; savage.
2. (UK dialectal, Scotland) Strong and fiery; biting; keen; sharp; pungent
3. (UK dialectal, Scotland) Very large; huge.
4. (obsolete) Eager; earnest; intent.

Adverb

1. Sharply; fiercely.