Defn: 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.

SEMILUNAR
Sem`i*lu"nar, n. (Anat.)

Defn: The semilunar bone.

SEMILUNARY
Sem`i*lu"na*ry, a.

Defn: Semilunar.

SEMILUNATE
Sem`i*lu"nate, a.

Defn: Semilunar.

SEMILUNE
Sem"i*lune`, n. (Geom.)

Defn: The half of a lune.

SEMIMETAL
Sem"i*met`al, n. (Chem.)