The term "mysterious man" refers to an individual who is enigmatic, elusive and difficult to understand. This person may have a secretive nature or engage in behaviors that are hard to decipher, leaving others feeling puzzled or intrigued by their actions. The phrase can also imply that the person has a certain air of mystery about them - perhaps they keep to themselves, are hard to read or possess hidden depths and complexities. Ultimately, the term "mysterious man" is used to describe someone who is difficult to fully understand or explain.