The Collaborative International Dictionary of English v.0.48:

Grass \Grass\ (gr[.a]s), n. [OE. gras, gres, gers, AS, gr[ae]s,
   g[ae]rs; akin to OFries. gres, gers, OS., D., G., Icel., &
   Goth. gras, Dan. gr[ae]s, Sw. gr[aum]s, and prob. to E.
   green, grow. Cf. Graze.]
   1. Popularly: Herbage; the plants which constitute the food
      of cattle and other beasts; pasture.
      [1913 Webster]

   2. (Bot.) An endogenous plant having simple leaves, a stem
      generally jointed and tubular, the husks or glumes in
      pairs, and the seed single.
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   Note: This definition includes wheat, rye, oats, barley,
         etc., and excludes clover and some other plants which
         are commonly called by the name of grass. The grasses
         form a numerous family of plants.
         [1913 Webster]

   3. The season of fresh grass; spring. [Colloq.]
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            Two years old next grass.             --Latham.
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   4. Metaphorically used for what is transitory.
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            Surely the people is grass.           --Is. xl. 7.
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   5. Marijuana. [Slang]
      [PJC]

   Note: The following list includes most of the grasses of the
         United States of special interest, except cereals. Many
         of these terms will be found with definitions in the
         Vocabulary. See Illustrations in Appendix.

The Collaborative International Dictionary of English v.0.48:

Grass \Grass\, v. t. [imp. & p. p. Grassed; p. pr. & vb. n.
   Grassing.]
   1. To cover with grass or with turf.
      [1913 Webster]

   2. To expose, as flax, on the grass for bleaching, etc.
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   3. To bring to the grass or ground; to land; as, to grass a
      fish. [Colloq.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grass \Grass\, v. i.
   To produce grass. [R.] --Tusser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grass
    n 1: narrow-leaved green herbage: grown as lawns; used as
         pasture for grazing animals; cut and dried as hay
    2: German writer of novels and poetry and plays (born 1927)
       [syn: Grass, Gunter Grass, Gunter Wilhelm Grass]
    3: a police informer who implicates many people [syn:
       supergrass, grass]
    4: bulky food like grass or hay for browsing or grazing horses
       or cattle [syn: eatage, forage, pasture, pasturage,
       grass]
    5: street names for marijuana [syn: pot, grass, green
       goddess, dope, weed, gage, sess, sens, smoke,
       skunk, locoweed, Mary Jane]
    v 1: shoot down, of birds
    2: cover with grass; "The owners decided to grass their
       property"
    3: spread out clothes on the grass to let it dry and bleach
    4: cover with grass [syn: grass, grass over]
    5: feed with grass
    6: give away information about somebody; "He told on his
       classmate who had cheated on the exam" [syn: denounce,
       tell on, betray, give away, rat, grass, shit,
       shop, snitch, stag]