ಅರ್ಥ : Something that baffles understanding and cannot be explained.
ಉದಾಹರಣೆ :
How it got out is a mystery.
It remains one of nature's secrets.
ಸಮಾನಾರ್ಥಕ : closed book, mystery, secret
ಅರ್ಥ : A difficult problem.
ಸಮಾನಾರ್ಥಕ : brain-teaser, conundrum, riddle