look up any word, like ratchet:
1) To lose intensity or dwindle in strength.
2) An exposed penis (peter).
Matt: "I bet I can streak through downtown with my peter out for two hours without getting arrested."
Frank: "I doubt it. After running for a half hour or so, you'll probably peter out and then the cops will catch you."
by Nicholas D March 09, 2009
The act of dropping out of a plan or leaving a party.
James: "Sorry guys, I have to head home."
Bob: "Don't peter out on us James!"
James: "Sorry man."
by Mitsuda August 08, 2007