| Noun | 1. | 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" | |
| 2. | HUM - 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 | |
| 3. | hum - a humming noise; "the hum of distant traffic"noise - sound of any kind (especially unintelligible or dissonant sound); "he enjoyed the street noises"; "they heard indistinct noises of people talking"; "during the firework display that ended the gala the noise reached 98 decibels" | |
| Verb | 1. | hum - sing with closed lips; "She hummed a melody"sing - produce tones with the voice; "She was singing while she was cooking"; "My brother sings very well" | |
| 2. | hum - be noisy with activity; "This office is buzzing with activity"be - have the quality of being; (copula, used with an adjective or a predicate noun); "John is rich"; "This is not a good answer" pullulate, swarm, teem - be teeming, be abuzz; "The garden was swarming with bees"; "The plaza is teeming with undercover policemen"; "her mind pullulated with worries" | |
| 3. | hum - sound with a monotonous humsound, go - make a certain noise or sound; "She went `Mmmmm'"; "The gun went `bang'" | |
| 4. | hum - make a low continuous sound; "The refrigerator is humming" | |