Power Violence is a musical genre combining hardcore punk and grindcore. Characterized by intense speed and radical tempo changes. Blast beats one moment to slow sludgy music the next.
Man is the Bastard officially coined the term Power Violence in their song Hispanic Small Man Power (H.S.M.P)

(noun) A person who sits on the front porch and intimidates, says negative things, or otherwise makes things unpleasant for those nearby.

A loosely defined sub-style of hardcore which almost completely eschews traditional song structure in favor of an all-out blitz-speed musical attack. More well-known power violence bands include Infest, Spazz, and Scholastic Deth.

An awesome form of music. (or Noise)
Influenced from punk and thrash.
Loud and fast as fuck, extremely difficult to understand.

A type of punk music that basically plays as fast as humanly possible with lyrics that don't even attempt to be audible or important.

Powerviolence is described in 3 words: "Noise Not Music."