astragal
A small molding that is semicircular in section; generally has a fillet on one or both sides; may be plain or ornamented. Photo from Philadelphia, Pennsylvania, 2017. 2. A molding attached to one or both meeting stiles of a pair of double doors to prevent drafts or the passage of light, noise, or smoke. (Phillips, 1994)
bead, baguette, bagnette, astragalus