Definition of "semilunar valve" []

• Either of two valves, one located at the opening of the aorta and the other at the opening of the pulmonary artery, each consisting of three crescent-shaped cusps and serving to prevent blood from flowing back into the ventricles. (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.