Home›Browse›P›pond scumpond scumOur editors are putting together more complete content — check back in about 20 minutespond scumpond scum — nounnoun1. a thin layer of algae or other plant material that grows on the surface of stagn1.nounDefinitiona thin layer of algae or other plant material that grows on the surface of stagnant waterExampleThe pond scum made the water look green and slimy.2. a very unpleasant or worthless person2.nounDefinitiona very unpleasant or worthless personExampleHe's nothing but pond scum for treating his friends that way.