WordNet sense 1 (very unpleasant):

god-awful, hellish

WordNet sense 2 (disagreeable to the senses, to the mind, or feelings ):

unpleasant

WordNet sense 3 (resembling a beast; showing lack of human sensibility):

bestial, brute, brutish

WordNet sense 4 (lacking and reflecting lack of pity or compassion):

inhumane