head-scratcher

head–scratcher

noun

Definition of HEAD-SCRATCHER

something hard to understand or explain <why he chose to sink all of his money into a failing business is a real head-scratcher>

Synonyms closed book, conundrum, enigma, head-scratcher, mystification, puzzle, puzzlement, riddle, secret

Related Words brainteaser, case, challenge, knot, matter, perplexity, poser, problem, stumper, trouble