Thesaurus

Synonyms for Sinister include:

alarming, anticlockwise, appalling, atrocious, awful, bad, baleful, black, bloodcurdling, chilling, contraclockwise, corruptive, counterclockwise, creepy, creepy-crawly, dark, demonic, despicable, devilish, diabolic, diabolical, dire, direful, dismaying, dread, dreaded, dreadful, evil, evil-minded, fearful, fearsome, fiendish, flagitious, forbidding, formidable, frightening, frightful, ghastly, grievous, grim, grisly, gruesome, hair-raising, hairy, heinous, hellish, horrendous, horrible, horrific, horrifying, immoral, infernal, left-handed, macabre, menacing, mephistophelean, mephistophelian, minacious, minatory, monstrous, nightmarish, offensive, ominous, perversive, pestiferous, petrifying, redoubtable, satanic, scarey, scary, shivery, shuddery, sick, sinister, sinistral, sinistrorsal, sinistrorse, slimy, stupefying, terrible, terrific, terrifying, threatening, ugly, unholy, unnerving, unrighteous, unworthy, vile, wicked, worthless, wretched, wrong

sinister is a ADJ.