Terrible.
ETYM Latin formidabilis, from formidare to fear, dread: cf. French formidable.
1. Extremely impressive in strength or excellence.
2. Inspiring fear; SYN. redoubtable, unnerving.
ETYM Latin tremendus that is to be trembled at, fearful, from tremere to tremble. Related to Tremble.
Astonishing because of its magnitude, force, or violence.