hmm
(verb, interjection)
interjection
1. Indicating thinking or pondering.
- Hmm... that's an interesting idea.
- Hmm... I just can't decide between the two.
2. A demand for an answer to a question.
- Just where were you until 2 a.m.? ... Hmm?
verb
1. (intransitive) To make a thoughtful humming noise.