Definition of costa in US English:



Botany Zoology
  • 1A rib, midrib, or riblike structure.

    • ‘The internal molds are smooth with exception of traces of the concentric costae on the rostral face.’
    • ‘It has strong divaricate ornamentation of coarse costae and/or small plicae, which bear low, close nodes, but which cover both the anterior and posterior faces of the shell.’
    • ‘Wall thickness is 10-26 m, becoming thicker at the corners of the chamber where it may bulge outwardly to produce coarse longitudinal costae.’
    • ‘The main part of the shell is coarsely commarginally lamellose and lacks radial costae.’
    • ‘He differentiated his new species from S. robusta by its more numerous costae on the shell flanks.’
    1. 1.1Entomology The main vein running along the leading edge of an insect's wing.
      • ‘It resulted in outgrowths and duplications of the costa region of the wing.’
      • ‘The forewings generally are reduced to the region immediately adjacent to the costa, having separated along the radius and cubitus veins.’


Mid 19th century: from Latin.