\Cos"tal\ (k?s"tal), a. [Cf. F. costal. See {Costa}.]
1. (Anat.) Pertaining to the ribs or the sides of the body;
   as, costal nerves.
2. (Bot. & Zo["o]l.) Relating to a costa, or rib.
{Costal cartilage}. See {Cartilage}, and Illust. of {Thorax}.