Showing execessive confidence or pride.
Similar word / Idiom
More often the word uppity (Uppity person is someone who behaves as if he / she is more important than others out of pride / arrogance pr simply – arrogant / self importance to a higher degree) also convey similar meaning.
When it comes to idiom to represent better than other people, we can use the term a cut above
Example
The overweening professor laughed at his students when they asked what he felt were stupid questions.
Her uppity boss always spoke about what a great job he did in his previous organization