in Architecture, a little round moulding, which in the orders surrounds the top of the shaft or body of the column. It is also called the talon and rondino; it is used at the bottoms as well as tops of columns, and on other occasions: it properly represents a ring, on whatever part of a column it is placed; and the original idea of it was that of a circle of iron put round the trunk of a tree, used to support an edifice, to prevent its splitting. The astragal is often cut into beads and berries, and is used in the ornamented entablatures to separate the several faces of the architrave.

in Gunnery, a round moulding encompassing a cannon, about half a foot from its mouth.