WordNet sense 1 (an official prohibition or edict against something):

ban, forbiddance, banning

WordNet sense 2 (harshly uninviting or formidable in manner or appearance):

dour, grim

WordNet sense 3 (disagreeable to the senses, to the mind, or feelings ):

unpleasant

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

baleful, menacing, minacious, minatory, ominous, sinister, threatening

WordNet sense 5 (causing alarm or fear):

alarming