Definition of "intercostal" [in•ter•cos•tal]

• Located or occurring between the ribs. (adjective)
• A space, muscle, or part situated between the ribs. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The ribs are situated one below the other in such a manner that spaces called intercostal spaces are left between them."
• "Eleven of them are situated between the ribs, and are therefore termed intercostal; the twelfth lies below the last rib."
• "The ribs are moved in respiration by two superficial muscular layers, known as the intercostal muscles."