astragal

noun8

1. •
   A semicircular molding separating the architrave at the top or bottom of a column.
2. •
   A circular molding near the mouth of a cannon.
3. •
   A molding attached to double doors to prevent drafts.
4. •
   Synonym of anklebone: the bone forming the ball of the ankle joint.
5. •
   A die, especially a four-sided die historically made from or in imitation of an ankle bone.
6. •
   A tool used to mold such features; similar tools used for connecting panes of glass in a window.
7. •
   Synonym of milkvetch: a plant of the genus Astragalus.
8. •
   A bracket used to fix downpipes to the wall of a building.