Conundrum

A Conundrum is a puzzling question. In one variety of conundrum, the question is posed as a riddle and the answer is or involves a pun. More broadly, a conundrum is any problem where the answer is very complex, possibly unsolvable without deep investigation. A mystery or paradox can often be phrased as a conundrum.

In the popular media

See also: Conundrum, Alice's Adventures in Wonderland, Conundrum (TNG episode), Countdown (game show), Mystery, Paradox