interjection
Definition: A sound made by humming, often used to show uncertainty or to fill a pause in conversation.
Example: "Hum, I'm not sure if that's the right answer," she said thoughtfully.
intransitive verb
Definition: To make a continuous low sound, like a bee or a person producing a tune without speaking.
Example: She likes to hum her favorite song while she works.
noun
Definition: A low, continuous sound made by someone humming or a similar sound.
Example: The hum of the refrigerator was the only noise in the quiet room.
transitive verb
Definition: To produce a low, continuous sound, often by singing a tune without using words.
Example: She began to hum her favorite song while cooking dinner.