| stickler(noun, difficulty, challenge, question, problem) |
| stumper(noun, difficulty, challenge, question, problem) |
| teaser(noun, difficulty, challenge, question, problem) |
| tough nut to crack(expression, idiom, question, secret, puzzle) |
| twister(noun, difficulty, challenge, question, problem) |
| why(noun, information, difficulty, reason, challenge) |
| seizer |
| abductor |
| aberration(noun, love, passion, desire, thing) |
| abstruseness(difficulty, question, secret, puzzle, perplexity) |
| accoutrement(noun, means, device, machine, tackle) |
| affidavit(noun, information, reason, picture, evidence) |
| affirmation(noun, information, mark, sign, indication) |
| annoyance(insult, stimulus, affront, incitement, goading) |
| anticipation(anxiety, confusion, doubt, uncertainty, whodunit) |
| appliance(noun, means, device, machine, tackle) |
| apprehension(anxiety, confusion, doubt, uncertainty, whodunit) |
| appropriator |
| argument(noun, information, reason, picture, evidence) |
| attestation(noun, information, mark, sign, reason) |