/ ˈgæskɪt; NAmE / noun
a flat piece of rubber, etc. placed between two metal surfaces in a pipe or an engine to prevent steam, gas or oil from escaping :
The engine had blown a gasket (= had allowed steam, etc. to escape) .
( figurative , informal )
He blew a gasket at the news (= became very angry) .
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WORD ORIGIN
early 17th cent.: perhaps from French garcette thin rope (originally little girl), diminutive of garce , feminine of gars boy.