What is pun? "I've always pictured myself taking selfies."

What is a pun?

In Italian, 'puntiglio' means "a fine point," hence a verbal quibble, and is most likely the source of the English "punctilious."

A pun is defined by Webster as "the humorous use of a word, or of words which are formed or sounded alike but have different meanings, in such a way as to play on two or more of the possible applications; a play on words."

via Pun Definitions (Pun of the Day).