1. the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
2. the chemical composition and properties of a substance or object
the chemistry of soil
3. the way two individuals relate to each other
their chemistry was wrong from the beginning -- they hated each other|a mysterious alchemy brought them together
4. That branch of science which treats of the composition of substances, and of the changes which they undergo in consequence of alterations in the constitution of the molecules, which depend upon variations of the number, kind, or mode of arrangement, of the constituent atoms. These atoms are not assumed to be indivisible, but merely the finest grade of subdivision hitherto attained. Chemistry deals with the changes in the composition and constitution of molecules. See Atom, Molecule.