mortmain

noun

1. (uncountable, usually)The perpetual, inalienable possession of lands by a corporation or non-personal entity such as a church.

   “1824, Charter of Incorporation of the Royal Asiatic Society of Great Britain and Ireland, [W]e do hereby grant our especial license and authority unto all and every person […] to grant sell alien and convey in mortmain unto and to the use of the said Society and their successors […]”

   “Though in truth it was the law of mortmain […] which originally sent the founders of chantries to seek the king's licence […]”

2. (literary, uncountable, usually)A strong and inalienable possession.

   “[…]; and some part of that influence [of the government], which would otherwise have been possessed as in a sort of mortmain and unalienable domain, returned again to the great ocean from whence it arose, […]”