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English definition of “hum”

hum

verb
 
 
/hʌm/ (present participle humming, past tense and past participle hummed)
SING [I, T] to sing without opening your mouth: She hummed to herself as she walked to school. I've forgotten the tune. Can you hum it to me?Singing in general
MAKE SOUND [I] to make a continuous, low sound: The computers were humming in the background.Sounds made by objects, movement or impact
be humming If a place is humming, it is busy and full of activity.Busy and activeHurrying and doing things quickly
hum noun [C] a low, continuous sound: the hum of traffic Sounds made by objects, movement or impact
(Definition of hum from the Cambridge Learners Dictionary © Cambridge University Press)
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