There are two parts to your question.
Yes, most people know what an anagram is. It's the same as synonym or eponymous. People know what it means, because it comes up if you study written words long enough. That said most people do not use the word in daily conversation, but that is only because it rarely comes up. Just because something is a low frequency word, does not mean that it is not well known. So yes, understood by many, but used very infrequently. Go right ahead and use it.