Escuage

Definition of Escuage

In feudeil law, service of the shield. One of the varieties of tenure in knight’s service, the duty imposed being that of accompanying the king to the wars for forty days, at the tenant’s own charge, or sending a substitute. In later times, this service was commuted for a certain payment in money, which was then called “escuage certain.” 2 Bl.Comm. 74, 75.

That's the definition of Escuage in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.