1 alarming, appalling, awful, dire, dread, dreadful, fearful, from hell (informal) ghastly, godawful (slang) grim, grisly, gruesome, harrowing, hellacious (U.S. slang) hideous, horrendous, horrible, horrid, lurid, macabre, petrifying, shocking, terrible, terrifying, traumatic, unnerving, unspeakable
2 annoying, awful, disagreeable, dreadful, extreme, great, insufferable, terrible, terrific, unpleasant, attractive, beautiful, calming, lovely, moderate, nice, pleasant, slight, soothing