There isn't really another single, universally accepted name for a pure substance. However, depending on the context, you could use terms like:

* Element: This is a pure substance that cannot be broken down further by chemical means.

* Compound: This is a pure substance made up of two or more different elements chemically combined in a fixed ratio.

* Single substance: This is a general term emphasizing that it is not a mixture.

Ultimately, the best alternative name depends on the specific situation and what you are trying to emphasize about the substance.