atrocious UK /əˈtɹəʊ.ʃəs/US /əˈtɹoʊ.ʃəs/ adjective3 •Frightful, evil, cruel, or monstrous.Prisons have been the sites of atrocious mistreatment of prisoners. •Very bad; abominable, disgusting.Their taste in clothes is just atrocious. •Offensive or heinous. formsmore atrocious · most atrocious