Lewis & Short

† hēmisphaerĭum, ĭi, n., = ἡμισφαίριον, a half-globe, hemisphere.

  1. I. In gen., Varr. R. R. 3, 5, 17; id. L. L. 7, § 7 Müll.; Hyg. Astr. 4, 13; Macr. Somn. Scip. 1, 15; 20; of the earth, Mela, 1, 1, 2; Mart. Cap. 6, § 602; 8, § 873 al.
  2. II. In partic., a cupola, dome, Vitr. 5, 10, 5.