frankmarriage
noun
: the tenure in feudal law by which a man and his wife held an estate granted by a blood relative of the wife in consideration of their marriage, whether before or after it, to be held of the donor by the issue of the marriage to not less than the fourth generation and without other service than fealty
called also liberum maritagium
Word History
Etymology
Middle English franke mariage, from Anglo-French fraunk mariage, literally, free marriage