A more thorough explanation:

A pretermitted defense is a type of defense used in legal cases involving wills and estates. It refers to a defense that is based on the fact that the testator (the person who made the will) did not include a certain person or entity in their will, either intentionally or unintentionally.

A pretermitted heir is a person who would have been entitled to inherit from the testator's estate if they had been included in the will, but who was not included for some reason. This can happen if the testator forgot to update their will after a major life event, such as the birth of a child.

A pretermitted-heir statute is a state law that provides protection for pretermitted heirs. Under this law, an omitted child or spouse can receive the same share of the estate as if the testator had died intestate (without a will), unless the omission was intentional. This means that if a child or spouse was left out of the will by mistake, they can still inherit from the estate.

For example, let's say that John creates a will that leaves his entire estate to his wife, Jane. However, John forgets to update his will after the birth of their child, Sarah. When John dies, Sarah would be considered a pretermitted heir because she was not included in the will. If the state where John lived has a pretermitted-heir statute, Sarah would be entitled to a share of John's estate, even though she was not mentioned in the will.