The Collaborative International Dictionary of English v.0.48:

Kneebrush \Knee"brush`\ (n[=e]"br[u^]sh`), n.
   1. (Zool.) A tuft or brush of hair on the knees of some
      species of antelopes and other animals; -- chiefly used in
      the plural.
      [1913 Webster]

   2. (Zool.) A thick mass or collection of hairs on the legs of
      bees, by aid of which they carry the collected pollen to
      the hive or nest; -- usually in the plural.
      [1913 Webster]