A supercluster is a group of galaxies that are very large and organized. They are usually found near the centers of large galaxies.
The billionth is a number that is very large. It's equal to 1,000,000,000. This number is so large that it's impossible to say it with words.
To annihilate something is to completely destroy it. You might annihilate a group of enemies or a whole city.
Denser means thicker. When you describe something as denser, you are saying that it is more concentrated or thicker than usual.
The subatomic level is the smallest level of the universe that we can see or measure. At the subatomic level, particles like atoms are still moving around.
A thing is gravitational if it attracts other things towards it. The Earth is gravitational, because it attracts objects towards it.
Unoriginal means that something is not very creative or innovative. Sometimes people use the word to describe something that is not very good or enjoyable.
To recede is to move back, to gradually move away from something. When the tide recedes, the water gradually moves away from the shore.