A more thorough explanation:

Definition: Ab irato (ab I-ray-toh) is a Latin term that means "by one who is angry." It is usually used to refer to a gift or devise made out of anger that is adverse to an heir's interests. At common law, an action to set aside this type of conveyance was known as an action ab irato.

Example 1: John was angry with his son for not following in his footsteps and becoming a lawyer. In his will, John left all his property to his daughter, ab irato, to spite his son.

Example 2: Mary was furious with her husband for cheating on her. She decided to sell their house and give all the money to charity, ab irato, without considering her husband's interests.

These examples illustrate the use of ab irato to describe a gift or devise made out of anger that is adverse to an heir's interests. In both cases, the testator acted out of anger and intentionally excluded their heirs from their inheritance.