Why not semisphere and hemicircle? Because σφαῖρα is Greek, it takes the Greek prefix ἥμι-, while circulus is Latin and takes the Latin prefix semi-. ̔Ημικύκλιον is Greek for semicirculus.

Why is it called hemisphere and not Hemisphere?

Hemisphere comes from the Greek, and combines the prefix hemi-, for "half," with sphere, or "perfectly round ball." We talk about the earth as divided at the equator into the northern and southern hemispheres (or divided at the prime meridian into eastern and western hemispheres).

Is the difference between hemisphere and Semisphere?

1 Answer. There is no difference when describing a shape. The origin of 'Hemi' is Greek, meaning half and 'Semi' is Latin. I have never heard anyone using the word semisphere.