stumper Synonyms

puzzler tough proposition successor stickler sticker sphinx seeker secret riddle rebus question quandary teaser trouble tough one fishing question whistle-stopper tough nut to crack brainteaser closed book toughie brain-teaser why twister puzzlement puzzle enigma dilemma difficulty cryptogram crux crosslet conundrum claimant challenge case eyeleteer floorer grabber problem poser petitioner perplexity paradox mystification mystery matter knot issue candidate