means A play on words that exploits multiple meanings or similar sounds for humorous effect.

from The word surfaced in the 17th century, but where it came from is honestly a mystery. The leading guess ties it to 'pundigrion,' itself a fanciful, possibly Italianate flourish (some point to 'puntiglio,' a fine point or quibble), with 'pun' as the clipped survivor. But scholars admit they're squinting in the dark here — the trail simply runs cold, which is a fittingly slippery fate for a word about slippery words.