Formidable
FORM'IDABLE, adjective [Latin formidabilis, from formido, fear.]
Exciting fear or apprehension; impressing dread; adapted to excite fear and deter from approach, encounter or undertaking. It expresses less than terrible, terrific, tremendous, horrible, and frightful.
They seemed to fear the formidable sight.
I swell my preface into a volume, and make it formidable when you see so many pages behind.