Emily Dickinson Lexicon

COST'AL, a. [Fr. costal, from L. costa, a coast, side or rib; Sp. costa, cost, and a coast; costear, to pay costs, to coast along. A coast or side is the extreme part, a limit, from extending, throwing or shooting out, Eng. to cast.]

Pertaining to the side of the body or the ribs; as costal nerves.