The Collaborative International Dictionary of English v.0.48:

Foxtail \Fox"tail`\, n.
   1. The tail or brush of a fox.
      [1913 Webster]

   2. (Bot.) The name of several kinds of grass having a soft
      dense head of flowers, mostly the species of Alopecurus
      and Setaria.
      [1913 Webster]

   3. (Metal.) The last cinders obtained in the fining process.
      --Raymond.
      [1913 Webster]

   Foxtail saw, a dovetail saw.

   Foxtail wedging. See Fox wedge, under Fox.
      [1913 Webster] fox trot