What is an antonym for hemisphere?

There isn't a direct antonym for "hemisphere" in the way that "hot" has an antonym "cold". However, depending on the context, you could consider these options:

If referring to the Earth:

* Whole Earth: This emphasizes the entire planet rather than a half.

* Globe: This is another word for the Earth.

If referring to a half of a sphere:

* Whole sphere: This focuses on the entire sphere, not just a half.

* Complete circle: This emphasizes the entirety of a circular shape, not just a semicircle.

Ultimately, the best antonym for "hemisphere" depends on the specific context in which it is used.