Definition from Wiktionary, the free dictionary
blowback (plural blowbacks)
- (firearms) A type of action where the pressure from the fired cartridge blows a sliding mechanism backward to extract the fired cartridge, chamber another cartridge, and cock the hammer.
- An unintended adverse result, especially of a political action.
- (slang) The act of shotgunning (inhaling from a pipe etc. and exhaling into another smoker's mouth).