sin·is·ter 
/ˈsɪnəstɚ/ adjective
/ˈsɪnəstɚ/ adjective [more sinister; most sinister] : having an evil appearance : looking likely to cause something bad, harmful, or dangerous to happen
▪ There was something sinister about him. ▪ He looked sinister. ▪ sinister black clouds
▪ There was something sinister about him. ▪ He looked sinister. ▪ sinister black clouds
— sin·is·ter·ly adverb
