The Collaborative International Dictionary of English v.0.48:

Cropper \Crop"per\ (kr?p"p?r), n.
   1. One that crops.
      [1913 Webster]

   2. A variety of pigeon with a large crop; a pouter.
      [1913 Webster]

   3. (Mech.) A machine for cropping, as for shearing off bolts
      or rod iron, or for facing cloth.
      [1913 Webster]

   4. A fall on one's head when riding at full speed, as in
      hunting; hence, a sudden failure or collapse. [Slang.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

cropper
    n 1: small farmers and tenants [syn: sharecropper, cropper,
         sharecrop farmer]

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "cropper":
   Bauer, agriculturalist, agriculturist, agrologist, agronomist,
   breakdown, coffee-planter, collapse, collective farm worker,
   comedown, crash, crofter, culbute, cultivator, deflation,
   dirt farmer, dive, downfall, dry farmer, fall, farm laborer,
   farmer, farmhand, flop, forced landing, gentleman farmer, granger,
   grower, harvester, harvestman, haymaker, header, husbandman,
   kibbutznik, kolkhoznik, kulak, muzhik, nose dive, peasant,
   peasant holder, picker, planter, plowboy, plowman, plunge,
   pratfall, raiser, rancher, ranchman, reaper, rustic, sharecropper,
   smash, sower, spill, sprawl, stumble, tailspin, tea-planter,
   tenant farmer, tiller, tree farmer, trip, truck farmer, tumble,
   yeoman



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

CROPPER, contracts. One who, having no interest in the land, works it in
consideration of receiving a portion of the crop for his labor. 2 Rawle, R.
12.