A more thorough explanation:

An in terrorem clause is a part of a will that says if someone challenges the will, they won't get what they were supposed to receive. This means that the person who challenges the will risks losing their inheritance. The purpose of this clause is to discourage people from challenging the will. However, in some states, this clause is not enforceable if there is a good reason to challenge the will.

Let's say that John's father passed away and left him a large sum of money in his will. However, John's sister believes that the will is not valid and decides to challenge it. If the will has an in terrorem clause, it means that if John's sister loses the challenge, she will not receive anything from the will. This is meant to discourage her from challenging the will in the first place.

Another example could be if a person leaves their estate to a charity, but their family members believe that they should have received a portion of the estate. If the will has an in terrorem clause, it means that if the family members challenge the will and lose, they will not receive anything from the estate.

These examples illustrate how an in terrorem clause can be used to discourage people from challenging a will. It is important to note that this clause is not always enforceable and can be challenged if there is a good reason to do so.