Sem′i‐lu″nar (?), a. Shaped like a half moon.
Semilunar bone(Anat.), a bone of the carpus; the lunar. See Lunar, n. — Semilunar, orSigmoid, 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.