Also called sem·i·cir·cum·fer·ence /ˌsɛmisərˈkʌmfərəns,-frəns,ˌsɛmaɪ-/Show Spelled[sem-ee-ser-kuhm-fer-uhns,-fruhns,sem-ahy-]Show IPA.half of a circle; the arc from one end of a diameter to the other.
2.
anything having or arranged in the form of a half of a circle.