Promutuum
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Lat. In the civil law. A quasi contract, by which he who receives a certain sum of money or a certain quantity of fungible things, which have been paid to him through mistake, contracts towards the payer the obligation of returning him as much.
Poth. de l'Usure, pt 3, a 1, a. 1.