The Collaborative International Dictionary of English v.0.48:
Tremendous \Tre*men"dous\, a. [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;
[1913 Webster] -- Tre*men"dous*ly, adv. --