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). Word Origin early 17th cent.: perhaps from French garcette
‘thin rope’ (originally ‘little girl’), diminutive of garce, feminine of gars ‘boy’.