Precarious Right
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
The right which the owner of a thing transfers to another, to enjoy the same until it shall please the owner to revoke it. If there is a time fixed during which the right may be used, it is then vested for that time, and cannot be revoked until after its expiration.
Wolff. Inst. § 333.
PRECARIUM (Lat.) The name of a contract among civilians, by which the owner of a thing, at the request of another person, gives him a thing to use as long as the owner shall please.
Poth. note 87. See Yelv. 172; Cro. Jac. 236; 9 Cow. (N. Y.) 687; Rolle, 128; Bac. Abr. "Bailment" (C); Ersk. Inst. 3. 1. 9; Wolflf. Inst. § 333.
A tenancy at will is a right of this kind.