Meaning of “puzzle” - Learner’s Dictionary

puzzle

noun [ C ] uk us /ˈpʌzl/
GAME

A2 a game or activity in which you have to put pieces together or answer questions using skill:

to do/solve a puzzle
a crossword puzzle
a jigsaw puzzle
SITUATION

a situation that is very difficult to understand:

Scientists have been trying to solve this puzzle for years.

(Definition of “puzzle noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)