busyness, hum (noun). the 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. Harkat-ul-Mujahidin, HUM, Harkat ul-Ansar, HUA, Harkat ul-Mujahedeen, Al Faran, Movement of Holy Warriors (noun).