/hwam"oh, wam"oh/ , Informal.
interj.
1. (used to indicate the sound of a blow, collision, falling object, etc.).
n.
2. immense energy; vigor: a movie with plenty of whammo to please the kids.
adj.
3. characterized by such a strong effect: a show with a whammo ending.
adv.
4. wham.
[ 1930-35; WHAM + -O ]