|Origin:||From the sound|
hum1 past tense and past participle hummed, present participle humming
1 [intransitive and transitive]
to sing a tune by making a continuous sound with your lips closed
hum to yourself
Tony was humming to himself as he drove along.
He began to hum a tune.
to make a low continuous sound:
Machines hummed on the factory floor.
3 [intransitive ]
if a place hums, it is full of activity - use this to show approval [↪ busy]:
By nine o'clock, the restaurant was humming.
The streets were humming with life.
4 British English
to take a long time deciding what to say or do [↪ hesitate; = hem and haw AmE]