Semicircle

n.	1.	The half of a circle; the part of a circle bounded by its diameter and half of its circumference.
	2.	A body in the form of half of a circle, or half of a circumference.
	3.	An instrument for measuring angles.

Noun

1.

semicircle - a plane figure with the shape of half a circle Synonyms: hemicycle

crescent, crescent moon, fifty percent, fifty-fifty, half, half circle, half-and-half, half-moon, hemicycle, hemisphere, horseshoe, lunula, lunule, mediety, meniscus, moiety, quadrant, scythe, sector, semisphere, sextant, sickle