The Collaborative International Dictionary of English v.0.48:

Cognisor \Cog`ni*sor"\ (? or ?), Cognisee \Cog`ni*see\, n.
   See Cognizor, Cognizee.
   [1913 Webster]

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

COGNISOR, English law. One who passes or acknowledges,a fine of lands or
tenements to another, in distinction from the cognisee, to whom the fine of
the lands, &c. is acknowledged.