Formidable
Formidable , adjective
[Latin formidabilis, from formidare to fear, dread: compare French formidable.]
Exciting fear or apprehension; impressing dread; adapted to excite fear and deter from approach, encounter, or undertaking; alarming.
They seemed to fear the formodable sight.
I swell my preface into a volume, and make it formidable, when you see so many pages behind.