A more thorough explanation:

Definition: Testatrix is an old-fashioned word that refers to a woman who makes a will. Nowadays, the term testator is used for both men and women who make a will.

Example: Mary was a wealthy woman who wanted to make sure her assets were distributed according to her wishes after she passed away. She consulted a lawyer to help her draft her will. As a testatrix, Mary had the right to decide who would inherit her property and possessions.

Explanation: The example illustrates how the term testatrix was used in the past to refer to a woman who made a will. Mary is referred to as a testatrix because she is a woman who is making a will. However, nowadays, the term testator is used regardless of gender identity.