A surfactant (or a mixture containing one or more surfactants) having cleaning properties in dilute solutions (soaps are surfactants and detergents).
Source:
PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 612 (https://doi.org/10.1351/pac197231040577)