| enigma(noun, trouble, show, dispute, difficulty) |
| riddle(noun, trouble, show, difficulty, challenge) |
| conundrum(noun, trouble, show, difficulty, challenge) |
| puzzle(noun, trouble, show, dispute, difficulty) |
| problem(noun, trouble, difficulty, issue, challenge) |
| secret(noun, adjective, trouble, challenge, secret) |
| closed book(noun, expression, idiom, trouble, challenge) |
| brain-teaser(noun, trouble, challenge, puzzle) |
| whodunit(noun, difficulty, question, secret, puzzle) |
| poser(noun, trouble, difficulty, challenge, question) |
| question(noun, trouble, issue, challenge, doubt) |
| mystification(noun, trouble, challenge, secret, puzzle) |
| arcanum(noun, secret) |
| puzzlement(noun, trouble, challenge, secret, puzzle) |
| romance(noun, excitement, allure, flight, adventure) |
| secrecy(noun, difficulty, challenge, dark, question) |
| why(noun, trouble, difficulty, reason, informal) |
| dilemma(noun, trouble, challenge, question, puzzle) |
| mystery story(noun, expression, idiom) |
| paradox(noun, trouble, challenge, problem, puzzle) |