1) One that is opposite or contrary to another,
2) An opponent or antagonist,
3) An antonym.
Looking at these three meanings we can infer that all three of them relatively mean the same thing. So now we must see in what way do we mean opposite. As in, do we mean a true opposite or do we mean an abstract opposite. We cannot consider an abstract opposite. An abstract opposite of something would be a “not-IT”. This is the logic used when people say that the opposite of a cat is a dog. But then again a parrot could also be an opposite of a cat. And with the logic that if two things are opposite to one thing then they must be the same, would mean that a dog and parrot is the same thing which is fundamentally incorrect. Another example is that of “What is the opposite of a spoon?” Some say to this “Fork”. But then what becomes of the knife? Therefore, we should consider a true opposite. Now how can we consider an opposite? Would a true opposite be something that is different from the original in its characteristics?