WordNet sense 1 (stemming from evil characteristics or forces; wicked or dishonorable):

black, dark

WordNet sense 2 (morally bad or wrong):

evil

WordNet sense 3 (of or on the left):

sinistral

WordNet sense 4 (threatening or foreshadowing evil or tragic developments):

baleful, forbidding, menacing, minacious, minatory, ominous, threatening

WordNet sense 5 (causing alarm or fear):

alarming