Dictionary 1. (n.) The half of a circle; the part of a circle bounded by its diameter and half of its circumference\.2. (n.) A semicircumference. 3. (n.) A body in the form of half of a circle, or half of a circumference. 4. (n.) An instrument for measuring angles. Thesaurus 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 |