or back pres·sure
[ bak-presh-er ]
/ ˈbækˌprɛʃ ər /
a resistant pressure exerted by liquid or gas against the forward motion or flow of an exhaust or pipe system: Careful control of backpressure ensures an even supply of oil from the well.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019