Mystery guy or mysterious guy

Hi,

"Mystery" is a noun. So it's a mysterious guy.

Regards

What about a miracle worker(isn't miracle also a noun?).I just thought that maybe mystery guy could be a compound noun; could you give a further explanation,please?

It can be. Especially in the same sense as a "secret admirer," some people might refer to a man who is mysterious as a "mystery guy." This most often just refers to a man of unknown identity.

A young woman has found out that a man she does not know has been asking questions about her at her place of employment. She tells a friend about it and they discuss possibilities of who the man m