What is Joint Lives?

Legal Definition
This expression is used to designate the duration of an estate or right which is granted to two or more persons to be enjoyed so long as they both (or nil) shall live. As soon as one dies, the interest determines. See High-iey v. Allen, 3 Mo. App. 524. As to joint "Adventure," "Ballot," "Committee," "Contract," "Covenant," "Creditor," "Executors," "Fiat," "Fine," "Heirs," "Indictment," "Session," "Tenancy," "Tenants," "Trespassers," and "Trustees," see those titles. As to joint-stock banks, see Bank; joint-stock company, see Company; joint-stock corporation, see Corporation.
-- Black's Law Dictionary
Legal Definition
A period ending upon the death of anyone of the persons named.
-- Ballentine's Law Dictionary