Source : Webster's Revised Unabridged Dictionary (1913)

Astragal \As"tra*gal\, n. [L. astragalus, Gr. ? the ankle bone,
   a molding in the capital of the Ionic column.]
   1. (Arch.) A convex molding of rounded surface, generally
      from half to three quarters of a circle.

   2. (Gun.) A round molding encircling a cannon near the mouth.

Source : WordNet®

astragal
     n 1: the bone in the ankle that articulates with the leg bones to
          form the ankle joint [syn: {anklebone}, {astragalus}, {talus}]
     2: a beaded molding for edging or decorating furniture [syn: {beading},
         {bead}, {beadwork}]