Defamation is a civil claim that one person may make against another. Michigan law defines it as one person making false statements about another that cause harm to the defamed person.
There are specific elements that you must prove to show the court that defamation occurred.
Statement
The first part of defamation requires someone to make a statement about you. It must be untrue, and you should be able to prove it is false.
Audience
The person must make the statement publicly or at least to one other person. It cannot be something they say to you and only you. Private communication with an insult is not defamation.
Harm
You need to suffer some type of harm to your reputation because of the false statement made by the person. Hurt feelings do not amount to harm that would allow you to file a defamation case. There must be measurable damage done to you because of this other person spreading lies about you.
A note
If you are a public figure, you may have a harder time proving defamation. The law does provide an exception in this situation. There is an added element where you would have to prove the other person was making the statements with the intent to harm you. Intent is not a requirement for a general defamation case.
Defamation can include slander and libel. It all depends on how exactly the person makes the statement and whether it is in writing or published. In general, though, defamation occurs when someone is spreading untruthful information, and it harms your reputation.