a game or toy that has a lot of pieces that you have to fit together [↪ jigsaw]:
a child's wooden puzzle
a game in which you have to think hard to solve a difficult question or problem:
a crossword puzzle
3 [usually singular]
something that is difficult to understand or explain
the puzzle of how the sun works
The meaning of the poem has always been a puzzle.
He thought he had solved the puzzle.
a piece of information that helps you to understand part of a difficult question, mystery etc