riddle

Main Entry: ¹rid·dle 

Pronunciation: \ˈri-d^əl\

Function: noun

Etymology: Middle English redels, ridel, from Old English rǣdelse opinion, conjecture, riddle; akin to Old English rǣdan to interpret — more at read

Date: before 12th century

1 : a mystifying, misleading, or puzzling question posed as a problem to be solved or guessed : conundrum, enigma
2 : something or someone difficult to understand

synonyms see mystery