What is a hynomyn?

Answer 1

words that sound like but have different meanings

Answer 2

There seems to be a typo in your question. If you meant to ask about a homonym, it refers to words that are spelled the same or sound the same but have different meanings. Examples include "bat" (flying mammal) and "bat" (a club used in sports) or "bark" (the sound a dog makes) and "bark" (the outer covering of a tree).