The word "unreal" is an adjective that describes something or someone as not being real, or lacking reality. It can refer to a situation or experience that seems dreamlike or surreal, where things happen that are difficult to believe or understand. In this sense, it means opposite of what is natural, genuine or true.
In additionally, "unreal" can also be used in the context of mathematics and computer science to describe something that does not exist in reality but only theoretically or virtually. For example, an unreal number is a mathematical concept that cannot be represented by any real number system.