definition of
hum

[1] #1 hum v. sing with closed lips; "She hummed a melody". wn

[2] #2 hum n. [busyness] 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". wn

[3] #3 hum n. [Harkat-ul-Mujahidin, HUM, Harkat ul-Ansar, HUA, Harkat ul-Mujahedeen, Al Faran, Movement of Holy Warriors] 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. wn

[4] #4 hum v. [buzz, seethe] be noisy with activity; "This office is buzzing with activity". wn

[5] #5 hum n. [humming] a humming noise; "the hum of distant traffic". wn