grumbles
grum-bles
verb
Expresses dissatisfaction or makes a low, rumbling sound, often from the stomach.
"He always grumbles about the cold."
noun
Minor complaints or expressions of dissatisfaction, often voiced quietly.
"There were a few grumbles about the food."
Thesaurus
Synonyms: murmuring, grumbling, murmur, mutter, grumble, muttering, growl, rumble, rumbling, scold, grouch, croak