terrible

daunting, demoralizing, disconcerting, discouraging, dismaying, disquieting, distressing, disturbing, perturbing, startling, threatening, troubling, trying, unnerving

bone-chilling, creepy, eerie (also eery), weird

appalling, atrocious, awful, grisly, gruesome (also grewsome), hideous, horrid, macabre, monstrous, nightmarish

accentuated, aggravated, concentrated, deepened

emphasized, enhanced, heightened, intensified, magnified

stressed

exhaustive, thorough

harsh, rigorous, severe

alarming, bloodcurdling, dire, direful, fearful, fearsome, forbidding, formidable, frightening, gut-wrenching, hair-raising, heart-stopping, intimidating, redoubtable, scary, terrifying

abhorrent, deplorable, disagreeable, disgusting, distasteful, loathsome, nauseating, noisome, obnoxious, obscene, offensive, repugnant, repulsive, revolting, sickening

abominable, evil, foul, heinous, noxious, odious, unspeakable, vile

grotesque, ugly, unsightly

bad, deficient, inferior, off, poor, substandard, wanting

contemptible, miserable, shameful

defective, faulty, flawed

low-grade, mediocre, reprehensible, second-rate

bum, useless, valueless, worthless

inadequate, insufficient, lacking

abominable, damnable, fiendish, odious, vile

useless, valueless, worthless

indifferent, lackluster, second-class

brummagem, flashy, garish, gaudy, glitzy, kitsch, kitschy, meretricious, ostentatious, showy, splashy, swank (or swanky), tawdry

seedy, shabby, tacky

counterfeit, fake, phony (also phoney), sham

supercheap, ultracheap