Formidable Moderate

extremely impressive in strength or excellence

"a formidable opponent"

"the challenge was formidable"

"had a formidable array of compositions to his credit"

"the formidable army of brains at the Prime Minister's disposal"

inspiring fear

"the formidable prospect of major surgery"

"a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"

"something unnerving and prisonlike about high grey wall"

Causing fear, dread, awe, or discouragement as a result of size, strength, or some other impressive feature; commanding respect; causing wonder or astonishment.

"The formidable mountain loomed against the dark sky, making climbers hesitate before attempting the ascent."