beastly

Short definition from Wiktionary

Adjective

1. 1
   Pertaining to, or having the form, nature, or habits of, a beast.
2. 2
   Similar to the nature of a beast; contrary to the nature and dignity of human beings.
3. 3
   Abominable; very unpleasant; hideous.
4. 4
   Of computer hardware or motor vehicles etc.: ostentatiously powerful.

Adverb

1. 1
   Like a beast; brutishly.