"Uhhh" is an unofficial word used when you don't know what to say, or you just... "uhhh".... don't know.

Literally everyone, ever. Including the writer of this definition.

elongated syllable used when dumbfounded

It's an answer like the others, probably one of the best answer

Uhhh (say it like Jay-Z) is a term created by the one named George Jones of Lehman PA. According to Jones, "Uhhh" is to be pulled out when there is awkward silence. It also may be used in the context for someone to stop talking about a particular subject because someone is in the room that they don't want to know about what the conversation is about..or just plain used to talk behind someones back.

As an ironic question, or a blank face expression, or a surprised look notion, to be used for internet based online chats.. Confusing to grasps the correlation between 2 topics while texting (sms) or texting via internet messengers..

a person that acts really slow