costa

costa (http://definr.com/costa)

     n 1: a riblike part of a plant or animal (such as a middle rib of
          a leaf or a thickened vein of an insect wing)
     2: any of the 12 pairs of curved arches of bone extending from
        the spine to or toward the sternum in humans (and similar
        bones in most vertebrates) [syn: rib]