Mordor is a fictional place from J.R.R. Tolkien's book "The Lord of the Rings." In the book, Mordor is depicted as a grim and terrible land where the main villain Sauron resides. It is a place full of volcanoes, smoke, and darkness, and it is hard to find anything alive or pleasant there. Thus, when someone wants to describe something dark and evil, they often use the word "Mordor."
So, what is Mordor in a cultural sense? It is a symbol of darkness and evil. People use this image to describe something very frightening or negative that creates a sense of hopelessness. For example, if someone says that the office they work in resembles Mordor, it means that the place is very unpleasant, possibly even exhausting.
Therefore, Mordor is not just a part of a fantasy world, but also a metaphor for describing dark and joyless places in real life.