| enigma(noun, show, difficulty, challenge, question) |
| puzzle(noun, show, difficulty, challenge, question) |
| mystery(noun, show, difficulty, challenge, question) |
| problem(noun, difficulty, challenge, question, disadvantage) |
| conundrum(noun, show, difficulty, challenge, question) |
| knot(noun, difficulty, bug, puzzle, impediment) |
| mystifier |
| perplexity(noun, show, difficulty, question, puzzle) |
| poser(noun, difficulty, challenge, question, puzzle) |
| teaser(noun, difficulty, challenge, question, problem) |
| confounder |
| crux(noun, difficulty, question, problem, puzzle) |
| floorer |
| mind-boggler(noun, challenge, doubt, question, problem) |
| question(noun, difficulty, problem, puzzle, mystery) |
| riddle(noun, show, difficulty, challenge, question) |
| stumper(noun, difficulty, challenge, question, problem) |
| annoyer |
| baffler |
| brainteaser(noun, difficulty, challenge, question, puzzle) |