WordWeb Online

1. The act of singing with closed lips
    
2. A humming noise
   "the humming of distant traffic";
   - hum

1. Sing with closed lips
   "She hummed a melody"
    
2. Be noisy with activity
   "This office is humming with activity";
   - buzz, seethe
    
3. Sound with a monotonous hum
   - thrum
    
4. Make a low continuous sound
   "The refrigerator is humming"
    
5. [Brit, informal] Smell badly and offensively
   - reek, stink

Derived forms: hummings

Type of: be, go, make noise, noise, resound, sing, singing, smell, sound, vocalising [Brit]

Encyclopedia: Humming