Definitions of costa:

• noun:   a riblike part of a plant or animal (such as a middle rib of a leaf or a thickened vein of an insect wing)
• noun:   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)
• name:  A surname (common: 1 in 9090 families; popularity rank in the U.S.: #1076)