Astragal
AS'TRAGAL, noun [Gr. a turning joint, vertebra, spondylus.]
1. In architecture, a little round molding which surrounds the top or bottom of a column, in the form of a ring; representing a ring or band of iron, to prevent the splitting of the column. it is often cut into beads or berries, and is used in ornamented entablatures to separate the several faces of the architrave.
2. In gunnery, a round molding on cannon near the mouth.
3. In anatomy, the buckle, ankle, or sling bone; the upper bone of the foot supporting the tibia.
4. In botany, the wood pea; the milk vetch; the liquorice vetch.