pow

Etymology 1

Onomatopoeic.

intj

1. The sound of a violent impact, such as a punch.
   Whap, Biff, Ooooof, Sock, Pow, Zok! Batman is back. Gotham City is again leaving its law and order in the hands of a man who wears plastic underpants over his tights. 5 Jun 1989, The Canberra Times, Australia Captial Territory, page 10, column 2
2. The sound of an explosion.
   Pow, they took off. 1982, Douglas Adams, Life, the Universe and Everything, page 71

noun

1. The sound of a violent impact.
2. The sound of an explosion.

Etymology 2

Variant forms.

noun

1. (Scotland, Ireland, Northern England) Alternative form of poll
   he'd snuffle round the door till the few remaining hairs on the bald pow of Munro would fair rise on end. 1932, Lewis Grassic Gibbon, Sunset Song (A Scots Quair), Polygon, published 2006, page 24
2. (skiing slang) Clipping of powder (“powder snow”).