IPA: /ˈfɪə.səm/
KK: /ˈfɪrˌsəm/
Causing fear or dread; frightening or intimidating.
The fearsome dragon guarded the treasure with fierce loyalty.
Comparative: more fearsome
Superlative: most fearsome
Fearsome → It is formed from "fear" (from Old English "fǣr", meaning a feeling of anxiety or dread) and "-some" (meaning characterized by or causing). The word "fearsome" describes something that is characterized by fear or that causes fear.
Think of something that causes a feeling of anxiety or dread — that's what fearsome means.