hum

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To emit a continuous low droning sound like that of the speech sound (m) when prolonged.
2. v. To emit the continuous droning sound of a bee on the wing; buzz.
3. v. To give forth a low continuous drone blended of many sounds: The avenue hummed with traffic.
4. v. To be in a state of busy activity.
5. v. To produce a tune without opening the lips or forming words.
6. v. To sing (a tune) without opening the lips or forming words.
7. v. Baseball To throw or pitch (a ball) very fast.
8. n. The sound produced by humming.
9. n. The act of humming.
10. interj. Used to indicate hesitation, surprise, or displeasure.

Century Dictionary and Cyclopedia

1. To make a prolonged droning sound, as a bee in flight; drone; murmur; buzz.
2. To give utterance to a similar sound, such as the droning of a tune, a contemptuous or vacant mumbling, a murmuring expression of applause or satisfaction, hesitation, dissent, etc.
3. Same as hem.
4. To sing with shut mouth, as to the sound m; murmur without articulation; mumble: as, to hum an air.
5. To express approbation of, or applaud, by humming.
6. n. Any inarticulate, low, murmuring, or buzzing sound, as that made by bees in flight, by a spinning top, etc.; a faint continuous sound having no definite pitch; a buzz.
7. n. Specifically— A low confused noise, as of a crowd, or of distant voices or sounds of any kind.
8. n. A buzz or murmur of applause or approbation.
9. n. A sound uttered with closed mouth by a speaker in a pause from embarrassment, affectation, or the like: as, hums and haws. Also (and now more commonly) hem.
10. n. A drink formerly common, probably made of strong ale or of ale and spirit. Its exact composition is not known.
11. An interjectional, hesitating sound, uttered with or during a pause; hem; h'm.
12. To trick or delude; impose on; cajole.
13. n. An imposition or hoax; a humbug.

Wiktionary

1. n. A hummed tune, i.e. created orally with lips closed.
2. n. An often indistinct sound resembling human humming.
3. n. Busy activity, like a beehive's buzz
4. n. UK, slang unpleasant odour.
5. v. intransitive To make a sound from the vocal chords without pronouncing any real words, with one's lips closed.
6. v. transitive To express of affect by humming
7. v. intransitive To drone like certain insects naturally do in motion, or sounding similarly
8. v. intransitive To buzz, be busily active like a beehive
9. v. intransitive To produce low sounds which blend continuously
10. v. UK To reek, smell bad.
11. v. UK To deceive, or impose on one by some story or device.
12. interj. hmm; an inarticulate sound uttered in a pause of speech implying doubt and deliberation.

GNU Webster's 1913

1. v. To make a low, prolonged sound, like that of a bee in flight; to drone; to murmur; to buzz.
2. v. To make a nasal sound, like that of the letter m prolonged, without opening the mouth, or articulating; to mumble in monotonous undertone; to drone.
3. v. To make an inarticulate sound, like h'm, through the nose in the process of speaking, from embarrassment or a affectation; to hem.
4. v. To express satisfaction by a humming noise.
5. v. To have the sensation of a humming noise.
6. v. To sing with shut mouth; to murmur without articulation; to mumble.
7. v. To express satisfaction with by humming.
8. v. Colloq. & Low To flatter by approving; to cajole; to impose on; to humbug.
9. n. A low monotonous noise, as of bees in flight, of a swiftly revolving top, of a wheel, or the like; a drone; a buzz.
10. n. Any inarticulate and buzzing sound.
11. n. The confused noise of a crowd or of machinery, etc., heard at a distance.
12. n. A buzz or murmur, as of approbation.
13. n. An imposition or hoax.
14. n. An inarticulate nasal sound or murmur, like h'm, uttered by a speaker in pause from embarrassment, affectation, etc.
15. n. obsolete A kind of strong drink formerly used.
16. interj. Ahem; hem; an inarticulate sound uttered in a pause of speech implying doubt and deliberation.

WordNet 3.0

1. n. an Islamic fundamentalist group in Pakistan that fought the Soviet Union in Afghanistan in the 1980s; now operates as a terrorist organization primarily in Kashmir and seeks Kashmir's accession by Pakistan
2. v. sound with a monotonous hum
3. n. a humming noise
4. n. the state of being or appearing to be actively engaged in an activity
5. v. be noisy with activity
6. v. sing with closed lips
7. v. make a low continuous sound