a. [ Cf. F. costal. See Costa. ] 1. (Anat.) Pertaining to the ribs or the sides of the body; as, costal nerves. [ 1913 Webster ]
2. (Bot. & Zool.) Relating to a costa, or rib. [ 1913 Webster ]
Costal cartilage. See Cartilage, and Illust. of Thorax. [ 1913 Webster ]
a. (Bot.) Having the nerves spring from the midrib. [ 1913 Webster ]