So Adam gave names to all cattle, to the birds of the air, and to every beast of the field (Genesis 2:20).

Genesis 11:7-9

This question has a couple of answers. Let me explain. First, Adam didn’t name every animal created or each variety and species. He would have only named the “kinds” of animals that God brought to him. (All of the varieties and species would not have been there yet!) In other words, he only named the dog kind, the cat kind, the horse kind, etc. 

Second, we don’t know what language Adam spoke, so there is really no way of knowing what he called each animal kind. And third, when God later confused all the languages at the Tower of Babel, it is possible that Adam’s original language did not survive (if it had survived, we still wouldn’t know what it was). As we study the Bible, we see that there is no way of knowing what Adam called the animals. But the names were probably not the same as today. Like for example, the word “dinosaurs.” The word wasn’t even invented until 1841, but we know from the Bible that these creatures were created along with the other animal kinds. But we do not know the name Adam gave them.