Conundrum
例
The meaning of life has always been a conundrum that philosophers have pondered for centuries.
人生の意味は、何世紀にもわたって哲学者が考えてきた難問でした。
02
a puzzling question or riddle, often involving wordplay, posed for amusement
例
The game included a series of conundrums to test the players' wit.
