[kos-tuh, kaw-stuh]
noun, plural cos·tae [kos-tee, kaw-stee] /ˈkɒs ti, ˈkɔ sti/.
  1. a rib or riblike part.
  2. the midrib of a leaf in mosses.
  3. a ridge.
  4. Entomology.
    1. Also called costal vein.a vein, usually marginal, in the anterior portion of the wing of certain insects.
    2. Also called costal margin.the anterior edge or border of the wing of certain insects.

Origin of costa

1865–70; < Latin: rib, side. See coast
Related formspseu·do·cos·ta, noun, plural pseu·do·cos·tae. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for costae

Historical Examples of costae

British Dictionary definitions for costae


noun plural -tae (-tiː)
  1. the technical name for rib 1 (def. 1)
  2. a riblike part, such as the midrib of a plant leaf
Derived Formscostal, adjective

Word Origin for costa

C19: from Latin: rib, side, wall
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for costae



Spanish costa "coast," from same Latin source as English coast (n.). Used in Britain from 1960s in jocular formations (costa geriatrica, costa del crime, etc.) in imitation of the names of Spanish tourist destinations.

Online Etymology Dictionary, © 2010 Douglas Harper

costae in Medicine


n. pl. cos•tae (-tē)
  1. Rib.
  2. A rodlike internal supporting organelle that runs along the base of the undulating membrane of certain flagellate parasites.basal rod
Related formscostal adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

costae in Science


Plural costae (kŏs)
  1. A rib or a riblike part, such as the midrib of a leaf or a thickened anterior vein or margin of an insect's wing.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.