Why is the Catholic Church called "The Roman Catholic Church"? If the word "catholic", from the Greek adjective καθολικός (katholikos), means "universal", why The Catholic Church is known as "The Roman Catholic Church"?

Is it possible be "universal" and "roman" at the same time?
The Catholic Church does indeed usually refer to itself just as "The Catholic Church". That is what it's Wikipedia article calls it (Wikipedia usually names all organizations according to what they call themselves). Many Catholic-related organizations just use the word "Catholic" in their names - CAFOD is an example; Catholic School boards are another. 

The term 'Roman Catholic' was originally applied by people who disagree with the Catholic church's claim to be the church (when they were not just referring to it as 'the Roman Church'). Over the centuries the usage has mutated, and term has been applied for various reasons, and is used by many people as if it were the official name of the church. However the history of the usage is extremely complicated. Even the Catholic Church sometimes refers to itself as the "Roman Catholic Church", especially if there is any danger of confusion, or of offence. This Wikipedia article gives some history of the usage of the term Catholic.

Those of you with way too much time on your hands can go and look through the Wikipedia debates on the correct naming of the church in the Catholic Church talk pages.