The Collaborative International Dictionary of English v.0.48:

Cultivator \Cul"ti*va`tor\ (k?l"t?-v?`t?r), n. [Cf. F.
   cultivateur.]
   [1913 Webster]
   1. One who cultivates; as, a cultivator of the soil; a
      cultivator of literature. --Whewell.
      [1913 Webster]

   2. An agricultural implement used in the tillage of growing
      crops, to loosen the surface of the earth and kill the
      weeds; esp., a triangular frame set with small shares,
      drawn by a horse and by handles.
      [1913 Webster]

   Note: In a broader signification it includes any complex
         implement for pulverizing or stirring the surface of
         the soil, as harrows, grubbers, horse hoes, etc.
         [1913 Webster] Cultrate

WordNet (r) 3.0 (2006):

cultivator
    n 1: someone concerned with the science or art or business of
         cultivating the soil [syn: agriculturist,
         agriculturalist, cultivator, grower, raiser]
    2: a farm implement used to break up the surface of the soil
       (for aeration and weed control and conservation of moisture)
       [syn: cultivator, tiller]