knights fee

from The Collaborative International Dictionary of English v.0.48

Knight's fee \Knight's fee\ (Feudal Law)
   The fee of a knight; specif., the amount of land the holding
   of which imposed the obligation of knight service, being
   sometimes a {hide[1](b)} or less, sometimes six or more
   hides.
   [Webster 1913 Suppl.]

from Bouvier's Law Dictionary, Revised 6th Ed (1856)

KNIGHT'S FEE, old Eng. law. An uncertain measure of land, but, according to 
some opinions it is said to contain six hundred and eighty acres. Co. Litt. 
69, a.