um
interjection
Meaning
An expression used to show contentment for something
"Mmm, this is a tasty pie!"
An expression used to show thought or reflection
"Mmm, I see what you mean."
An expression used to show being muffled or not able to speak clearly, as well as "mmph".
Yes.
verb
Meaning
To make the um sound to express uncertainty or hesitancy.
interjection
Meaning
Expression of hesitation, uncertainty or space filler in conversation. See uh.
"Let’s see... um... how about this?"