Astragal

1. n. A round molding encircling a cannon near the mouth.
2. n. A convex molding of rounded surface, generally from half to three quarters of a circle.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.