\A*gist"er\, Agistor \A*gist"or\, n. [Anglo-Norman
agistour.] (Law)
(a) Formerly, an officer of the king's forest, who had the
    care of cattle agisted, and collected the money for the
    same; -- hence called {gisttaker}, which in England is
    corrupted into {guest-taker}.
(b) Now, one who agists or takes in cattle to pasture at a
    certain rate; a pasturer. --Mozley & W.