Fluvius
The Cyclopedic Law Dictionary · Walter A. Shumaker and George Foster Longsdorf; ed. James C. Cahill · 1922
The Cyclopedic Law Dictionary
(Lat.) In old English law.
A river
Fluvii regales, royal streams. Public rivers for public passage (Fr. haut stremes le roy). So called, not in reference to the ownership of the river, but to the public use; all things of public safety and convenience being, in a special manner, under the king's care, supervision, and protection.