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blow-by

or blow·by

[bloh-bahy]
noun, plural blow-bies. Automotive.
  1. leakage of the air-fuel mixture or of combustion gases between a piston and the cylinder wall into the crankcase of an automobile.
  2. a device, fitted to a crankcase, for conducting such gases back to the cylinders for combustion.
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Origin of blow-by

First recorded in 1930–35; noun use of verb phrase blow by
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for blow-by

blow-by

noun
  1. the leakage of gas past the piston of an engine at maximum pressure
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012