The Lewis-Langmuir theory, also known as the surface adsorption theory, is an essential concept in physical chemistry. It explains the behavior of gases and liquids at the interface of a solid or liquid surface. Synonyms for the Lewis-Langmuir theory include the Langmuir adsorption model, Langmuir isotherm, surface chemistry, adsorption equilibrium, and surface tension. The Langmuir isotherm model is used to describe the extent of adsorption of a gas on a solid surface at a given temperature and pressure. Surface chemistry involves the study of the chemical reactions that occur at the interface of a solid or liquid surface. Overall, these synonyms highlight the significance of the Lewis-Langmuir theory in understanding the behavior of materials at surfaces.