Source : Webster's Revised Unabridged Dictionary (1913)

Rush \Rush\, n. [OE. rusche, rische, resche, AS. risce, akin to
   LG. rusk, risch, D. & G. rusch; all probably fr. L. ruscum
   butcher's broom; akin to Goth. raus reed, G. rohr.]
   1. (Bot.) A name given to many aquatic or marsh-growing
      endogenous plants with soft, slender stems, as the species
      of {Juncus} and {Scirpus}.

   Note: Some species are used in bottoming chairs and plaiting
         mats, and the pith is used in some places for wicks to
         lamps and rushlights.

   2. The merest trifle; a straw.

            John Bull's friendship is not worth a rush.
                                                  --Arbuthnot.

   {Bog rush}. See under {Bog}.

   {Club rush}, any rush of the genus {Scirpus}.

   {Flowering rush}. See under {Flowering}.

   {Nut rush}
      (a) Any plant of the genus {Scleria}, rushlike plants with
          hard nutlike fruits.
      (b) A name for several species of {Cyperus} having
          tuberous roots.

   {Rush broom}, an Australian leguminous plant ({Viminaria
      denudata}), having long, slender branches. Also, the
      Spanish broom. See under {Spanish}.

   {Rush candle}, See under {Candle}.

   {Rush grass}, any grass of the genus {Vilfa}, grasses with
      wiry stems and one-flowered spikelets.

   {Rush toad} (Zo["o]l.), the natterjack.

   {Scouring rush}. (Bot.) Same as {Dutch rush}, under {Dutch.}
      

   {Spike rush}, any rushlike plant of the genus {Eleocharis},
      in which the flowers grow in dense spikes.

   {Sweet rush}, a sweet-scented grass of Arabia, etc.
      ({Andropogon sch[oe]nanthus}), used in Oriental medical
      practice.

   {Wood rush}, any plant of the genus {Luzula}, which differs
      in some technical characters from {Juncus}.

Source : WordNet®

rush grass
     n : grass having wiry stems and sheathed panicles [syn: {rush-grass}]