Inter vivos is a legal term referring to a transfer or gift made during one's lifetime, as opposed to a testamentary transfer (a gift that takes effect on death).

The term is often used to describe a trust established during one's lifetime, i.e., an Inter vivos trust as opposed to a Testamentary trust

Testamentary trust

A testamentary trust is a trust which arises upon the death of the testator, and which is specified in his or her will...

which is established on one's death, usually as part of a will

Will (law)

A will or testament is a legal declaration by which a person, the testator, names one or more persons to manage his/her estate and provides for the transfer of his/her property at death...

. An Inter vivos trust is often used synonymously with the more common term Living trust, but an Inter vivos trust, by definition, includes both revocable and irrevocable trust.

The term inter vivos is also used to describe living organ donation

Organ donation

Organ donation is the donation of biological tissue or an organ of the human body, from a living or dead person to a living recipient in need of a transplantation. Transplantable organs and tissues are removed in a surgical procedure following a determination, based on the donor's medical and...

, in which one patient donates an organ to another while both are alive. Generally, the organs transplanted are non-vital. A common example of this practice is the inter vivos transplantation of kidneys.