Definition of "hum"
hum
/ˈhʌm/
noun
plural hums
(UK, slang) Unpleasant odour.
(dated) An imposition or hoax; humbug.
verb
third-person singular simple present hums, present participle humming, simple past and past participle hummed
interjection
Synonym of hmm: a noise indicating thought, consideration, &c.
Synonym of um: a noise indicating doubt, uncertainty, &c.