1. a plane figure with the shape of half a circle;

[syn:

The Collaborative International Dictionary of English v.0.48:

Semicircle \Sem"i*cir`cle\, n. 1. (a) The half of a circle; the part of a circle bounded by its diameter and half of its circumference. (b) A semicircumference. [1913 Webster] 2. A body in the form of half of a circle, or half of a circumference. [1913 Webster] 3. An instrument for measuring angles. [1913 Webster]Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "semicircle": 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