As a verb frighting
As an adjective frightful is
(obsolete): full of fright; affrighted; frightened.
* frightfull (archaic)
(obsolete): Full of fright; affrighted; frightened.
Full of that which causes fright; exciting alarm; impressing terror; shocking; as, a frightful chasm, or tempest; a frightful appearance.
(Used as an intensifier)
- We wasted a frightful amount of money on renovations.