surfactant

n. soap like substance that decreases the surface tension of liquids in order for the liquid to spread out and improve wetting; (Medicine) mixture of phospholipids secreted by the the cells of the alveoli in the lungs which reduces the surface tension of pulmonary fluids and helps to the elastic characteristics of pulmonary tissue

This article is about surfactants in general. For the compound produced by alveolar cells, see pulmonary surfactant. Surfactants, also known as tensides, are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids.
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Surfactant is a complex naturally occurring substance made of six lipids and four proteins that is produced in the lungs. [more]Surfactant - Community and Resources

Noun
1. a substance capable of reducing the surface tension of a liquid in which it is dissolved
(synonym) wetting agent, wetter, surface-active agent
(hypernym) chemical agent
(hyponym) emulsifier

soap like chemicals added to solutions to reduce surface tension and improve wetting.