Whodunit
Etymology
A deliberate coinage from illiterate-sounding grammar: "Who done it?" It was minted in 1930 by the American book reviewer Donald Gordon, who used it flippantly to describe a mediocre detective novel. The joke — dignifying a whole genre with ungrammatical slang — stuck, and the word outlasted the review by nearly a century.
noun · /hoo-DUN-it/
A mystery story whose central puzzle is the identity of the culprit.
What it names
A precise genre label — and, by extension, a handy word for any real situation whose main question is simply "who did this?"
Example
The office turned the missing-stapler saga into a full whodunit, complete with suspects and alibis.
Related idea
A thriller keeps you tense about what will happen next; a whodunit keeps you guessing about what already happened, and by whom.
See also