n. 25B6; noun this situation's a bit of a poser : DIFFICULT QUESTION, vexed question, awkward problem, tough one, puzzle, mystery, conundrum, puzzler, enigma, riddle; informal dilemma, facer, toughie, stumper.
POSER
Meaning of POSER in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012