grumble

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To complain in a surly manner; mutter discontentedly: "The governed will always find something to grumble about” ( Crane Brinton).
2. v. To rumble or growl.
3. v. To express in a grumbling discontented manner: grumbled a rude response.
4. n. A muttered complaint.
5. n. A rumble; a growl.

Century Dictionary and Cyclopedia

1. To make a low rumbling sound; mutter; growl.
2. To complain in a low, surly voice; murmur with discontent.
3. Synonyms To complain, repine, croak.
4. To express or utter in a grumbling or complaining manner.
5. n. The act of grumbling; a grumbling speech or remark.
6. n. A surly person.
7. n. plural A grumbling, discontented mood; a fit of the spleen.

Wiktionary

1. n. onomatopoeia A low thundering, rumbling or growling sound
2. n. The sound made by a hungry stomach
3. n. A complaint
4. v. intransitive To make a low, growling or rumbling noise, like a hungry stomach or certain animals.
5. v. intransitive To complain.
6. v. transitive To utter in a grumbling fashion.

GNU Webster's 1913

1. v. To murmur or mutter with discontent; to make ill-natured complaints in a low voice and a surly manner.
2. v. To growl; to snarl in deep tones.
3. v. To rumble; to make a low, harsh, and heavy sound; to mutter.
4. v. To express or utter with grumbling.
5. n. The noise of one that grumbles.
6. n. A grumbling, discontented disposition.

WordNet 3.0

1. v. make complaining remarks or noises under one's breath
2. n. a complaint uttered in a low and indistinct tone
3. n. a loud low dull continuous noise
4. v. make a low noise
5. v. to utter or emit low dull rumbling sounds
6. v. show one's unhappiness or critical attitude