dread, scarey, spine-chilling, fearful, terrific, noble, spooky, baleful, formidable, grim, stupefying, dreaded, august, shuddery, horrific, bloodcurdling, minacious, solemn, portentous, gruesome, atrocious, nightmarish, majestic, macabre, scary, horrendous, direful, sinister, stately, menacing, redoubtable, forbidding, imposing, fearsome, hair-raising, shivery, chilling, hairy, minatory, eerie, creepy, awesome, creepy-crawly, grand, ominous, grisly, ugly
alarming (part of speech: verb)
frightening (part of speech: verb)
frightening, disquieting, panicking, intimidating, distressing, dangerous, rattling, horrifying, scaring, setting on edge, terrifying, unnerving, disturbing, haunting, harrowing, agitating, petrifying
warning (part of speech: verb)
awful (part of speech: adjective)
- More alarming than she is now? - "What Maisie Knew", Henry James.
- But the moment we left the drawing- room the thing was clear, though not the less marvellous and alarming. - "The Seaboard Parish, Complete", George MacDonald.
- She called up Miss Carstairs in the first excitement of- of your accident, it seems, and I'm afraid she gave a very exaggerated and alarming account, you know. - "Captivating Mary Carstairs", Henry Sydnor Harrison.