Akademik

grumbling
I
noun
1. a loud low dull continuous noise (Freq. 1)
-

they heard the rumbling of thunder

Syn: ↑rumble, ↑rumbling, ↑grumble
Derivationally related forms: ↑grumble, ↑grumble (for: ↑grumble), ↑rumble (for: ↑rumbling), ↑rumble (for: ↑rumble)
Hypernyms: ↑noise
2. a complaint uttered in a low and indistinct tone (Freq. 1)
Syn: ↑grumble, ↑murmur, ↑murmuring, ↑mutter, ↑muttering
Derivationally related forms: ↑mutter (for: ↑muttering), ↑mutter (for: ↑mutter), ↑murmur (for: ↑murmuring), ↑murmur (for: ↑murmur), ↑grumble, ↑grumble (for: ↑grumble)
Hypernyms: ↑complaint
II
adjective
continuous full and low-pitched throbbing sound
-

the rumbling rolling sound of thunder

Syn: ↑rumbling
Similar to: ↑full

Useful english dictionary. 2012.