Definition of "backflow" [backflow]

• A flow of fluid in the opposite direction of its regular flow. (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.

• "Joe the Plumber, who found his name repeated again and again by Barack Obama and John McCain during one of the 2008 presidential debates, has somehow bubbled up, like some kind of backflow, into the debate over Proposition B, the ballot measure to bring commonsense standards to large-scale dog breeding operations in the largest of the puppy mill states."
• "However, it is also near an area of the northern Gulf where a "backflow" pushes west towards the western Louisiana and upper-Texas coastlines."
• "Abnormal development of the tricuspid valve during pregnancy, causing an abnormally positioned valve that does not open easily (stenosis) and allows backflow of blood from the right ventricle into the right atrium (regurgitation)."