Synonyms of perplexities

1 Syllable
sphinx, why, rune, crux
2 Syllables
stumper, thriller, twister, rebus, poser, question, puzzle, stickler, occult, teaser, puzzler, chiller, riddle, grabber, problem
3 Syllables
cryptogram, enigma, whodunit, brainteaser, braintwister, mindboggler, puzzlement, conundrum, charade, oracle, secrecy, subtlety, cliffhanger
4 Syllables
abstruseness, difficulty
5 Syllables
inscrutableness, mystification
6 Syllables
inscrutability