Dear Ana Carolina Pimenta, "fizzle out" is actually hard to explain, but it means something like to pass, to finish, to vanish, for example you have a dog and your dog gets killed by a car, but the driver of this car flees and he never gets caught by the police, and after a time your sadness about the dog gets less, than it "fizzles out", so it means that something gets less and less attention after you forget it... Im sorry for my complicated explanation, it's actually really hard hahah Hope it helped you a little bit... Felix

It is a common metaphor. The literal reference is to a firecracker (foguete) (or some other explosive device), with a fuse (fusível). Normally, you light the fuse. You back away to a safe distance. The fuse burns at a rate of about 1 cm/second. It makes a fizzling sound as it burn--"it fizzles." After fifteen seconds or so, the firecracker explodes. Sometimes, though, the fuse just stops burning. It "fizzles out." You are expecting a "bang," but all you got was a "fizzle." It means "something that seemed to be progressing, came to a disappointing stop." Here is an example of how it could be used, metaphorically, in a political context. "After every school shooting, there has been a push to pass gun control laws. But, so far, every time, the efforts have fizzled out." Another example: "Bitcoin Falls Back Below $10,000 As Recovery Fizzles Out."

It is an informal phrasal verb that means: "to gradually become less successful and end in a disappointing way" (from Oxford Learner's Dictionary) "to gradually end, often in a disappointing or weak way" (from Cambridge Dictionary) Do you perhaps have the context in which "fizzle out" was used?

Dan got it right. Fizzle has to do with something like a candle or firecracker that's burning (fizzle is to burn), but then the fire burns out and is gone. Thus, the fire fizzled out. That's where the expression comes from, and that's its literal meaning. But, as in Dan's examples, it's not limited to a literal meaning, and can be metaphorical and mean like fading away, or losing steam, or force. That's all it means. His examples sentences were good. There are several little synonyms for it, like fade out, peter out, lose steam. There's probably others I can't think of off the top of my head.