Meaning of surface-active agent

sur'face-ac•tive a'gent

Pronunciation: (sûr'fis-ak"tiv), [key]
— Chem. Chem.
  1. any substance that when dissolved in water or an aqueous solution reduces its surface tension or the interfacial tension between it and another liquid. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.