Vassal

A vassal[1] or liege subject[2] is a person regarded as having a mutual obligation to a lord or monarch, in the context of the feudal system in medieval Europe. The obligations often included military support by knights in exchange for certain privileges, usually including land held as a tenant or fief.[3] The term is also applied to similar arrangements in other feudal societies.

In contrast, fealty (fidelitas) was sworn, unconditional loyalty to a monarch.[4]