Definition

A non-committal filler response deployed when you know the answer but don't want to admit it, don't know the answer but won't say so, or simply want to annoy someone. Maximum ambiguity, minimum effort.

Example Usage

When asked if he finished the project, he just replied 'Ummm...' and walked away.

Source: Urban Dictionary (https://www.urbandictionary.com/define.php?term=ummm&defid=6340484)