Pronunciation: (kō"ärk-tā'shun), [key]
a. a narrowing of the lumen of a blood vessel.
b. a congenital anomaly of the heart in which there is a narrowing of the aorta, resulting in abnormal blood flow.
2. Entomol.the condition of having the body enclosed in a hardened shell or puparium.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.