The term hemi-spheres generally refers to halves of a sphere or half of a brain. There are various synonyms available for this word depending on the context in which it is used. In terms of science, the word "demi-sphere" can be used as a synonym for hemisphere. Other synonyms include "semi-globes," "half-spheres," and "demi-globes." These synonyms are often used interchangeably in geography, anatomy, and other scientific fields. However, it's always important to pay attention to the context of the word before using any of the synonyms to avoid miscommunication.