From Longman Dictionary of Contemporary Englishgrumblinggrum‧bling /ˈɡrʌmblɪŋ/ noun 1 [uncountable] (also grumblings [plural]) a complaint about something She paid up, with some grumbling. Soon, the grumblings turned to open discontent.2 [uncountable] a low continuous sound the grumbling of distant thunder
Examples from the Corpus
grumbling• To their creaking and grumbling was added a new note, comparable to music.• In many cases, however, it is expressed as an intermittent grumbling of practitioners rather than as a systematic counter-argument.• A muted grumbling followed, then the slamming of a door. 