a loud low dull continuous noise;
"they heard the rumbling of thunder"
a complaint uttered in a low and indistinct tone
continuous full and low-pitched throbbing sound;
"the rumbling rolling sound of thunder"
- Taxpayers are grumbling about the waste of government money as usual.
- Stop grumbling! You've got nothing to complain about.
- She has no patience with (ie cannot tolerate) people who are always grumbling.
- I'm fed up with your grumbling.