Uh

1.A buffer word used to stall
2. A verbal reflex used to create time to think
3. Can sometimes replace the word (not letter) 'a' depending on your accent

1. Person 1: You came home late. What were you doing last night?

Person 2: Uhhhhhhhhhhhhhhhhhhhhhhh....
2. Person 1: What's two plus two?

Person 2: Two plus two? Uh, four...I think.
3. "I went to get uh bag of apples from the store."