The Collaborative International Dictionary of English v.0.48:

Arpentator \Ar`pen*ta"tor\, n. [See Arpent.]
   The Anglicized form of the French arpenteur, a land surveyor.
   [R.]
   [1913 Webster]

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

ARPENTATOR, from arpent. A measurer or surveyor of land.