WordNet sense 1 (harshly ironic or sinister):

black, mordant

WordNet sense 2 (expressing or expressive of ridicule that wounds):

sarcastic

WordNet sense 3 (harshly uninviting or formidable in manner or appearance):

dour, forbidding

WordNet sense 4 (disagreeable to the senses, to the mind, or feelings ):

unpleasant

WordNet sense 5 (not to be placated or appeased or moved by entreaty):

inexorable, relentless, stern, unforgiving, unrelenting, unappeasable

WordNet sense 6 (incapable of being placated):

implacable

WordNet sense 7 (characterized by hopelessness; filled with gloom):

gloomy, darkening

WordNet sense 8 (without hope because there seems to be no possibility of comfort or success):

hopeless

WordNet sense 9 (causing dejection):

blue, dark, depressing, dingy, disconsolate, dismal, drab, drear, dreary, sorry, dispiriting, dingy

WordNet sense 10 (lacking cheer; depressing):

uncheerful

WordNet sense 11 (shockingly repellent; inspiring horror):

ghastly, grisly, gruesome, macabre, sick

WordNet sense 12 (causing alarm or fear):

alarming