Making a low, continuous musical sound with your mouth closed; also a persistent buzzing sound.
From Old English 'hum,' an imitative word meant to copy the sound itself. The '-ing' form creates the present participle, indicating an ongoing action.
Humming might seem like a simple thing, but it's one of the few activities that simultaneously uses your voice box without actual speech—which is why humming a tune can actually activate both language and music processing in your brain at the same time.
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