Liberum Servitium
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Free service
Service of a warlike sort by a feudatory tenant; sometimes calied "servitium Uberum armorum." Jacob. Service not unbecoming the character of a freeman and a soldier to perform; as to serve under the lord in his wars, to pay a sum of money, and the like.
2 Bl. Comm. 60.