Definition of "surfactant" []

• A surface-active substance. (noun)
• A substance composed of lipoprotein that is secreted by the alveolar cells of the lung and serves to maintain the stability of pulmonary tissue by reducing the surface tension of fluids that coat the lung. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Synthetic surfactant is used to help immature lungs rest and heal."
• "Dr. Avery ultimately identified a mix of fat and proteins in the lungs that came to be called surfactant."
• "Thanks to the March of Dimes, a substance called surfactant had been developed that helped a premature baby's undeveloped lungs work."