It's not a word game. Anselm's argument is circular. Like in "greater", he includes existence. That's the mistake Gaunilo pointed to, which is a valid refutation. His reply is quite weak, first saying it only applies to God, which makes the whole point meaningless and false, because what you can conceive in your mind is not God. So his starting point is false from his own admission. So the whole argument fails. Then he includes being a creator as being greater, which is quite subjective. Basically he shifts the goalpost as he goes along, while forgetting he is trying to make a reasonable argument. This being said, scholasticism is an important development and people should study it for what it is, because it's what gave us the scientific method. Anselm's argument is irrelevant to that effect.
