The Collaborative International Dictionary of English v.0.48:

Pasture \Pas"ture\, n. [OF. pasture, F. p[^a]ture, L. pastura,
   fr. pascere, pastum, to pasture, to feed. See Pastor.]
   1. Food; nourishment. [Obs.]
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            Toads and frogs his pasture poisonous. --Spenser.
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   2. Specifically: Grass growing for the food of cattle; the
      food of cattle taken by grazing.
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   3. Grass land for cattle, horses, etc.; pasturage.
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            He maketh me to lie down in green pastures. --Ps.
                                                  xxiii. 2.
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            So graze as you find pasture.         --Shak.
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The Collaborative International Dictionary of English v.0.48:

Pasture \Pas"ture\, v. t. [imp. & p. p. Pastured; p. pr. & vb.
   n. Pasturing.]
   To feed, esp. to feed on growing grass; to supply grass as
   food for; as, the farmer pastures fifty oxen; the land will
   pasture forty cows.
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The Collaborative International Dictionary of English v.0.48:

Pasture \Pas"ture\, v. i.
   To feed on growing grass; to graze.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pasture
    n 1: a field covered with grass or herbage and suitable for
         grazing by livestock [syn: pasture, pastureland,
         grazing land, lea, ley]
    2: bulky food like grass or hay for browsing or grazing horses
       or cattle [syn: eatage, forage, pasture, pasturage,
       grass]
    v 1: let feed in a field or pasture or meadow [syn: crop,
         graze, pasture]
    2: feed as in a meadow or pasture; "the herd was grazing" [syn:
       crop, browse, graze, range, pasture]

Moby Thesaurus II by Grady Ward, 1.0:

165 Moby Thesaurus words for "pasture":
   appetite, arable land, barley, barnyard, barton, batten upon,
   bird seed, board, bran, bread, browse, campo, cannibalism,
   carnivorism, carnivority, carnivorousness, cat food, cattle ranch,
   chewing, chicken farm, chicken feed, chop, collective farm,
   consumption, corn, cotton plantation, croft, crop, cropping,
   dairy farm, deglutition, demesne, demesne farm, devouring,
   devourment, dieting, dine, dining, dog food, dry farm, dude ranch,
   eatage, epulation, factory farm, fallow, farm, farmery, farmhold,
   farmland, farmplace, farmstead, farmyard, fatten on, fatten upon,
   feast on, feast upon, feasting, feed, feed on, feeding, fodder,
   forage, fruit farm, fur farm, gluttony, gobbling, grain,
   grain farm, grange, grass, grass veld, grassland, gratify, graze,
   grazing, hacienda, haugh, haughland, hay, herbivorism, herbivority,
   herbivorousness, homecroft, homefarm, homestead, hunger, ingestion,
   kibbutz, kolkhoz, lea, licking, live on, llano, location, mains,
   manducation, manor farm, mash, mastication, mead, meadow,
   meadow land, meal, meat, mess, messing, munching, nibbling,
   nutrition, oats, omnivorism, omnivorousness, omophagy, orchard,
   pampa, pampas, pantophagy, park, pasturage, pasture land,
   pasture on, pasturing, pecking, pen, pet food, plantation,
   poultry farm, prairie, prey on, provender, provision, ranch,
   rancheria, rancho, range, regale, regalement, relishing,
   rumination, satisfy, savanna, savoring, scratch, scratch feed,
   sheep farm, silage, slops, station, steading, steppe, steppeland,
   stock farm, straw, sustain, swale, swill, tasting, toft,
   truck farm, vega, vegetarianism, veld, wheat, wine and dine,
   wolfing