In order to make a will, a person must intend to make a will. A person must have what is known as testamentary intent. The adjective 'testamentary' means related to a will, and is a derivative of the word 'testament'--the Latin word for will. The Latin phrase for testamentary intent is animus testandi, "the intention to make a testament."
In Latin, a testament is what a person has to say. It is the same root of the words 'testify' and 'testimony'--words which refer to what a witness has to say in court. A will, or testament, is what a person has to say about what the person desires after death. If a person dies leaving a will, the person is said to have died testate. The status is known as testacy. If a person dies without leaving a will, the person is said to have died intestate. The status is known as intestacy.
Traditionally, a male person who makes a will is known as a testator and a female person who makes a will in known as a testatrix. Today, testator means the maker of a will, whether male or female.
Suppose a person signs an instrument. Is it the person's will? It is the person's will only if the person who signs the instrument knows that the instrument is a will and signs it as a testator, not as a witness. If the person does not intend that the instrument be a will, it is not a will.
Suppose a person is forced to sign an instrument against his or her will (in the sense of desire). Is it the person's will? No. An instrument signed against one's will is said to have been signed under duress. Duress is unlawful pressure to act (such as having the point of a loaded gun held to one's head). It invalidates what would otherwise be a valid will.
It is easy to overlook the importance of testamentary intent. One common error occurs when a husband and wife make their wills at the same time. What happens is that the wills can get mixed up such that the husband and wife sign each other's will by mistake. In a strict sense, there is a violation of the requirement of testamentary intent. The husband intended to sign his will and his wife intended to sign her will. They didn't intend to sign their spouse's will. In many states, such a mistake means that neither the husband nor the wife have made a will. Some states, however, have made a judicial exception for this kind of mistake, ruling that there was testamentary intent and a judicially-correctable clerical error.
The requirement of testamentary intent will also invalidate a will, or a portion thereof, because of fraud. Fraud is intentional misrepresentation or concealment. "Fraud in the execution" is a deception regarding the character of an instrument. It invalidates the entire instrument. There is no will, for example, if the person signed believing that he or she was signing an election petition. "Fraud in the inducement" is a deception regarding the circumstances under which an instrument is made. It invalidates the relevant portion of the instrument. In a will with a gift to an named grandchild, for example, the gift is invalidated if the testator was tricked into believing that the person he gave the gift to was his grandchild.