From WordNet (r) 3.0 (2006):
hum
n 1: 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"
[syn: busyness, hum]
2: 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 [syn: Harkat-ul-Mujahidin,
HUM, Harkat ul-Ansar, HUA, Harkat ul-Mujahedeen, Al
Faran, Movement of Holy Warriors]
3: a humming noise; "the hum of distant traffic" [syn: hum,
humming]
v 1: sing with closed lips; "She hummed a melody"
2: be noisy with activity; "This office is buzzing with
activity" [syn: hum, buzz, seethe]
3: sound with a monotonous hum [syn: hum, thrum]
4: make a low continuous sound; "The refrigerator is humming"