hmm

Etymology

See hum.

intj

1. Indicating thinking or pondering.
   Hmm... that's an interesting idea.
   Hmm... I just can't decide between the two.
   Hmm... creation or evolution? That’s the big question.
   Jeeves: Foreign travel often liberates emotions best kept in check, sir. The air of North America is notoriously stimulating in this regard, as witness the regrettable behavior of its inhabitants in 1776. B. Wooster: Hmm? What happened in 1776, Jeeves? Jeeves: I prefer not to dwell on it, if it's convenient to you, sir. May 12 1991, “Kidnapped!”, in Jeeves and Wooster, season 2, episode 5
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.