(1):

(n.) A grumbling, discontented disposition.

(2):

(v. i.) To murmur or mutter with discontent; to make ill-natured complaints in a low voice and a surly manner.

(3):

(v. t.) To express or utter with grumbling.

(4):

(v. i.) To growl; to snarl in deep tones; as, a lion grumbling over his prey.

(5):

(v. i.) To rumble; to make a low, harsh, and heavy sound; to mutter; as, the distant thunder grumbles.

(6):

(n.) The noise of one that grumbles.