While "-ant" is a common suffix, it doesn't necessarily tell us what the word means. In this case, it signifies that the word is a noun describing someone who does something.
To understand "tyrant" fully, we need to look at the root word "tyrann-", which comes from the Greek word "tyrannos," meaning "ruler."
So, a tyrant is someone who rules in a harsh, oppressive, and unjust way.