لغز riddle
something which is confusing, or a problem which is difficult to solve

Scientists may have solved the riddle of Saturn's rings
من المحتمل ان يكون العلماء قد حلّوا لغز حلقات زحل

The police have been unable to solve the riddle of her disappearance
لم تستطع الشرطة أن تحلّ لغز إختفائها

No one could provide an answer to the riddle of Marilyn's death
لم بتمكن أحد من أن يأتي بإجابة على لغز موت مارلين