hum

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"

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

a humming noise; "the hum of distant traffic"

sing with closed lips; "She hummed a melody"

be noisy with activity; "This office is buzzing with activity"

sound with a monotonous hum

make a low continuous sound; "The refrigerator is humming"