fizzle /ˈfɪzəl/noun 4verb 3forms 3phrases 1 noun4 •A spluttering or hissing sound. •Failure of an exploding nuclear bomb to meet its expected yield during testing. •An abortive effort; a flop or dud. •A state of agitation or worry. verb3 •To sputter or hiss.The soda fizzled for several minutes after it was poured. •To fail to generate the expected yield when exploded during testing.The shot fizzled, generating only 200 tons rather than the 30 kilotons they were aiming for. •(informal, figurative) To decay or die off to nothing; to burn out; to end less successfully than previously hoped.The entire project fizzled after the founder quit. formsfizzled · fizzling · fizzles Phrases with fizzle fizzle outTo lose excitement, to become less exciting; to end, fail or die out in a weak or disappointing way.