\Knot"grass`\, n. (Bot.)
(a) a common weed with jointed stems {(Polygonum aviculare)};
    knotweed.
(b) The dog grass. See under {Dog}.
Note: An infusion of {Polygonum aviculare} was once supposed
      to have the effect of stopping the growth of an animal,
      and hence it was called, as by Shakespeare, ``hindering
      knotgrass.''
            We want a boy extremely for this function, Kept
            under for a year with milk and knotgrass. --Beau.
                                               & Fl.