Open English Wordnet
Nouns
(n)busyness, humthe state of being or appearing to be actively engaged in an activity“they manifested all the busyness of a pack of beavers”,
“there is a constant hum of military preparation” (n)hum, humminga humming noise“the hum of distant traffic” Verbs
(v)humsing with closed lips“She hummed a melody” (v)hum, buzz, seethebe noisy with activity“This office is buzzing with activity” (v)hum, thrumsound with a monotonous hum (v)hummake a low continuous sound“The refrigerator is humming”