Wiktionary
vb. (context idiomatic English) To become less virulent.
WordNet
v. suffer from a disease that kills shoots; "The plants near the garage are dying back" [syn: die back]
become progressively weaker; "the laughter died down"
Usage examples of "die down".
In time the volcanoes will die down, and vegetation will spread all over.
He left the lecture hall, but the clamor didn't die down behind him.
Data sat attentively, obviously waiting to speak, and Riker let the low drone of conversation die down by itself.
Then we saw that the huge fire was beginning to die down, revealing a vast bed of glowing coals.
Hoke waited for the noise to die down, then he looked at Lord Ivran with a steady, crucial eye.
And I'm about ready to do that right now, if you'll let that fire die down to a bed of coals fit to cook over.
They kept the fire going, after letting it die down a little, sitting about it while their cloaks and surcoats steamed dry.