HUM

[verb] -mm- - to make a continuous low soundBees, mosquitoes and certain other insects and birds hum. [I]I think there's something wrong with the television - it's humming. [I]Debbie often hums (= sings a tune with her lips closed) (to herself) while she's listening to music. [I]I've forgotten how that tune goes - could you hum it for me? [T]What's that strange humming sound?(figurative) The pub was really humming (with life/activity) (= it was busy and full of activity) last night. [I]We (UK and ANZ) hummed and hah-ed/hawed (US hemmed and hawed) (= were uncertain and took a long time) before deciding to buy the house.