Mystery/ˈmɪstəri/ Definition 1 of 4Pro Tip 1/3Unsolved Questions Use 'mystery' when something can't be explained or understood, often after much thought. How the pyramids were built is still a mystery. Pro Tip 2/3Intriguing Uncertainty 'Mystery' adds a sense of intrigue or interest when you talk about unresolved issues. Her sudden disappearance was surrounded by mystery. Pro Tip 3/3Seeking Answers When 'mystery' is used, it suggests something people want or are trying to figure out. Scientists are unraveling the mysteries of the universe.