brain-teaser Synonyms

enigma riddle conundrum unsolved problem teaser stumper strait sphinx secret roun riddled rebus question quandary tickler twister Riddles question mark Chinese puzzle brainteaser closed book whodunit mystery story koan word game jigsaw puzzler why puzzlement puzzle problem dilemma difficulty crux confusion complication complexity charade bewilderment arcanum anagram abstrusity distraction doubt embarrassment predicament poser plight perplexity paradox