adjective

frightening, especially in appearance.

the cat mewed, displaying a fearsome set of teeth

frightening,horrifying,terrifying,menacing,chilling,spine-chilling,hair-raising,alarming,startling,unnerving,daunting,formidable,forbidding,dismaying,mean-looking,disquieting,disturbing,harrowing,appalling,dreadful,monstrous,horrendous,awe-inspiring,awesome,impressive,imposing,tremendous,scary,hairy