causing fear or dread or terror; "the awful war"; "an awful risk"; "dire news"; "a career or vengeance so direful that London was shocked"; "the dread presence of the headmaster"; "polio is no longer the dreaded disease it once was"; "a dreadful storm"; "a fearful howling"; "horrendous explosions shook the city"; "a terrible curse"
Fearsome is used to describe things that are frightening, for example because of their large size or extreme nature. He had developed a fearsome reputation for intimidating people. a fearsome array of weapons. = formidable. very frightening