hmm

interj. you use this sound to show you are thinking about something or considering an idea.

interj. used to indicate that the speaker is engaged in thought, reflection, or deliberation.

“Hmm, I'm not sure if I can come to the party on Saturday.”

“Hmm, that is an interesting proposal, though I will need to consult with the rest of the department before committing to a budget.”

Informal

interj. a sound you make when you are surprised or didn't hear what someone said.

interj. indicates surprise, mild confusion, or a request for repetition when addressed unexpectedly.

“Hmm? Sorry, I wasn't listening to you just then.”

“Hmm? I didn't realize the meeting had already started while I was away from my desk.”

Informal

interj. a sound used at the end of a question to show you are waiting for the other person to answer.

interj. used as a prompt or a tag question to elicit a response or confirmation from the listener.

“It's a beautiful day for a walk, hmm?”

“You haven't actually finished the report yet, hmm?”

Informal