grumbling (Adjective) — Continuous full and low-pitched throbbing sound. ex. "the grumbling rolling sound of thunder"
grumbling (Noun) — A loud low dull continuous noise. ex. "they heard the grumbling of thunder"
grumbling (Noun) — A complaint uttered in a low and indistinct tone.
grumbling (Verb) — Show one's unhappiness or critical attitude. ex. "We grumbled about the increased work load"
grumbling (Verb) — Make complaining remarks or noises under one's breath. ex. "she grumbles when she feels overworked"
grumbling (Verb) — To utter or emit low dull rumbling sounds. ex. "he grumbled a rude response" ex. "Stones grumbled down the cliff"
grumbling (Verb) — Make a low noise. ex. "grumbling thunder"