Tremendous, a.
Etymology: [L. tremendus that is to be trembled at, fearful, fr. tremere to tremble. See Tremble.]
Fitted to excite fear or terror; such as may astonish or terrify by its magnitude, force, or violence; terrible; dreadful; as, a tremendous wind; a tremendous shower; a tremendous shock or fall. A tremendous mischief was a foot. Motley.
Syn. -- Terrible; dreadful; frightful; terrific; horrible; awful. -- Tre*men"dous*ly, adv. -- Tre*men"dous*ness, n.
Shades of meaning
Fernald has no entry of its own for tremendous; he lists it under formidable.
Where he writes about it:
Formidable is a word of more dignity than dangerous, and suggests more calm and collected power than terrible; formidable is less overwhelming than tremendous. — from formidable
A loaded gun is dangerous; a park of artillery is formidable; a charge of cavalry is terrible; the full shock of great armies is tremendous. — from formidable
A dangerous man is likely to do mischief, and needs watching; a formidable man may not be dangerous if not attacked; an enraged maniac is terrible; the force of ocean waves in a storm, and the silent pressure in the ocean depths, are tremendous. — from formidable