It has a funny sound to it doesn't it? Grumble....mumble, mumble, so phonasthetic.grum·ble (grŭm'bəl)
v., -bled, -bling, -bles.
v.intr.
To complain in a surly manner; mutter discontentedly: “The governed will always find something to grumble about” (Crane Brinton).
To rumble or growl.
v.tr.
To express in a grumbling discontented manner: grumbled a rude response.
n.
A muttered complaint.
A rumble; a growl.
[Probably Dutch grommelen, to mutter, from Middle Dutch, frequentative of grommen.]
grum'bler n.
grum'bling·ly adv.
grum'bly adj.
Thesaurus
grumble
verb
To complain in low indistinct tones: grunt, murmur, mutter. See happy/unhappy, sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.
To make a continuous deep reverberating sound: boom, growl, roll, rumble. See sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.
noun
A low indistinct utterance of complaint: grunt, murmur, mutter. See happy/unhappy, sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.
Katy