[stoi.chi.om.e.try] n [Gk stoicheion element (fr. stoichos row) + E -metry; akin to Gk steichein to walk, go--more at stair] (1807) 1: a branch of chemistry that deals with the application of the laws of definite proportions and of the conservation of mass and energy to chemical activity
2. a: the quantitative relationship between constituents in a chemical substance b: the quantitative relationship between two or more substances esp. in processes involving physical or chemical change