Hmm vs. Umm
Difference Between Hmm and Umm
Indicating thinking or pondering.Hmm... that's an interesting idea.Hmm... I just can't decide between the two.
Interjection implying hesitation; see um.- How does a plane fly?- Umm, I don't know.
A demand for an answer to a question.Just where were you until 2 a.m.? Hmm?
To make the umm sound to express confusion or hesitancy.
(intransitive) To make a thoughtful humming noise.