Any chemical entity.

Chemical element and its compound, either in the natural state or obtained by a production process, including any additive necessary to preserve the stability of the product and any impurity derived inevitably from the process used, but excluding any solvents that can be separated without affecting the stability of the substance or changing its composition

A chemical.

The word "substance" is used to mean chemical elements and their compounds in the natural state or obtained by any production process, including any additive necessary to preserve the stability of the product. In the European legislation, only the word "substance" is used.

EPER definition: any chemical element and its compounds, with the exception of radioactive substance