Inter vivos (Latin, between the living) 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 which is established on one's death, usually as part of a will. 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, 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.