semilunar valve

noun

: either of two heart valves of which one occurs between the heart and the aorta and the other between the heart and pulmonary artery and that consist of three crescent-shaped flaps that are forced apart by pressure in the ventricles during systole and pushed together by pressure in the arteries during diastole and which prevent regurgitation of blood into the ventricles

also : any of the crescent-shaped flaps making up the semilunar valves

Word History

First Known Use

circa 1719, in the meaning defined above

Medical Definition

semilunar valve

noun

1

: either of two valves of which one is situated at the opening between the heart and the aorta and the other at the opening between the heart and the pulmonary artery, which prevent regurgitation of blood into the ventricles, and each of which is made up of three crescent-shaped cusps that are forced apart by pressure in the ventricles exerted during systole and are pushed together by pressure in the arteries exerted during diastole

2

: semilunar cusp