Hypertext Webster Gateway: "valves"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
Semilunar \Sem`i*lu"nar\, a.
Shaped like a half moon.
{Semilunar bone} (Anat.), a bone of the carpus; the lunar.
See {Lunar}, n.
{Semilunar}, or {Sigmoid}, {valves} (Anat.), the valves at
the beginning of the aorta and of the pulmonary artery
which prevent the blood from flowing back into the
ventricle.
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