portentous
adjective /pɔːˈtentəs/
  /pɔːrˈtentəs/
- (literary) important as a sign or a warning of something that is going to happen in the future, especially when it is something unpleasant
- a portentous sign
 
 - (formal, disapproving) very serious and intended to impress people synonym pompous
- a portentous remark