Sentence:  Fief: m[asculine] "A" <WSD>Fief</WSD>. A (Knights) fee, a Mannor, or inheritance held by homage, and fealty; and given at the firſt, in truſt, and upon promiſe of aſſiſtance, or ſervice in the wars: ... Alſo, a Tenure, or Eſtate in <WSD>fief</WSD>, or in fee. This word was firſt heard of, after the conqueſt of "Gallia" by the "Francs" (or ancient French-men) when their Soveraign Princes, reſerving ſome land for their own Domains, diſtributed the reſt (by whole Countreys, or large territories) among their Captains, and principal followers, on condition, that they ſhould hold of them, and aid them in their wars ... 
Meaning of the word marked with <WSD> tags:  An estate held by a person on condition of providing military service to a superior.