Adjective

• S: (adj) baleful, forbidding, menacing, minacious, minatory, ominous, sinister, threatening (threatening or foreshadowing evil or tragic developments) "a baleful look"; "forbidding thunderclouds"; "his tone became menacing"; "ominous rumblings of discontent"; "sinister storm clouds"; "a sinister smile"; "his threatening behavior"; "ugly black clouds"; "the situation became ugly"
• S: (adj) black, dark, sinister (stemming from evil characteristics or forces; wicked or dishonorable) "black deeds"; "a black lie"; "his black heart has concocted yet another black deed"; "Darth Vader of the dark side"; "a dark purpose"; "dark undercurrents of ethnic hostility"; "the scheme of some sinister intelligence bent on punishing him"-Thomas Hardy
• S: (adj) sinister (on or starting from the wearer's left) "bar sinister"