Uh Definition

ŭ
interjection
Webster's New World
Used to express hesitation or uncertainty.
American Heritage
Used when hesitating in speaking, as while searching for a word or collecting one's thoughts: a prolonged sound.
Webster's New World

(US) Space filler or pause during conversation.

Uh, let me see...
Wiktionary
noun
An occurrence of the interjection "uh".
Wiktionary