from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The climactic phrase or statement of a joke, producing a sudden humorous effect.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The final part of a joke; the word, sentence, or exchange of sentences that is intended to be funny and provokes laughter from the listeners.
from the GNU version of the Collaborative International Dictionary of English
- n. The final sentence, phrase, or word in a joke or humorous story that is unexpected and produces the humorous effect; the point of a joke.
- n. The final sentence, phrase, or word in any narration, speech, or advertisement that produces the speaker's intended effect.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the point of a joke or humorous story
punch + line, probably American. It was probably meant to be likened to a quick, sharp punch. (Wiktionary)