Chem. designating or of a substance, as a detergent or wetting agent, that lowers the surface tension of the solvent in which it is dissolved or the tension at the interface between two immiscible liquids
See surface-active in American Heritage Dictionary 4
sur·face-ac·tive
adjective
Of, relating to, or being a substance capable of reducing the surface tension of a liquid in which it is dissolved. Used especially of detergents.