The state of being busy.
Busy activity, like the buzz of a beehive.
Unpleasant odour.
A phenomenon, or collection of phenomena, involving widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise not audible to all people.
A hummed tune, i.e. created orally with lips closed.
An often indistinct sound resembling human humming.
To produce low sounds which blend continuously
To express by humming.
To reek, smell bad.
To make a sound from the vocal chords without pronouncing any real words, with one's lips closed.
To drone like certain insects naturally do in motion, or sounding similarly
To buzz, be busily active like a beehive
Synonym of um: a noise indicating doubt, uncertainty, &c.
Synonym of hmm: a noise indicating thought, consideration, &c.