A vavasour, (also vavasor, Old French vavassor, vavassour, French vavasseur, LL. vavassor, probably from vassus vassorum "vassal of the vassals") is a term in Feudal law. A vavasour was the vassal or tenant of a baron, one who held their tenancy under a baron, and who also had tenants under him. Alternative spellings include: vavasour, valvasor, vasseur, vasvassor, oavassor, and others.
In its most general sense the word thus indicated a mediate vassal, i.e. one holding a fief under a vassal. The word was, however, applied at various times to the most diverse ranks in the feudal hierarchy, being used practically as the synonym of vassal. Thus tenants-in-chief of the crown are described by the Emperor Conrad II as valvassores majores, as distinguished from mediate tenants, valvassores minores. Gradually the term without qualification was found convenient for describing sub-vassals, tenants-in-chief being called capitanei or barones; Its implication, however, still varied in different places and times. Bracton ranks the magnates seu valvassores between barons and knights; for him they are "men of great dignity," and in this order they are found in a charter of Henry II of England (1166). But in the regestum of Philip II Augustus we find that five vavassors are reckoned as the equivalent of one knight. Finally, Du Cange quotes two charters, one of 1187, another of 1349, in which vavassors are clearly distinguished from nobles.
The derivation of the word vavassor is very obscure. The fanciful interpretation of Bracton, vas sortitum ad valetudinem (a vessel chosen to honor), may be at once rejected. Others would derive it from vassi ad valvas (at the folding-doors, valvae), i.e. servants of the royal antechamber. Du Cange regards it merely as an obscure variant of vassus.