1. A play on words: This is the most common meaning. A pun is a form of humor that uses a word or phrase with multiple meanings, or words that sound alike but have different meanings, for a humorous effect.
Example: "I'm reading a book about anti-gravity. It's impossible to put down!"
This pun uses the word "put down" in two ways: literally meaning to set the book down, and figuratively meaning to find something interesting and hard to stop reading.
2. An intended ambiguity: This definition is less common, but it refers to a statement or expression that can be interpreted in two or more ways, often intentionally. This can be used for humorous effect, but it can also be used for more serious purposes, like creating suspense or emphasizing a point.
Example: "Time flies like an arrow. Fruit flies like a banana."
This pun plays on the similar sound of "flies" in two different contexts, highlighting the absurdity of the second statement.
So, the meaning of "pun" depends on the context, but it generally refers to a play on words, a joke, or an intentional ambiguity.