An upstart is someone who has recently gained wealth, power, or success and acts in a way that others find too bold or pushy. The word carries a critical edge: it suggests someone who doesn't show proper respect for people who've been established longer or who acts more important than they really are.

Imagine a new student joining your school mid-year who immediately starts telling everyone how things should be done, acts like they're in charge, and dismisses the opinions of kids who've been there longer. That newcomer might be called an upstart. Or picture a small company that just started last year acting like it can boss around businesses that have been operating successfully for decades.

Today, we use it for anyone who rises quickly and shows what others see as arrogance or disrespect toward those already established.

Calling someone an upstart is rarely a compliment. It suggests that the speaker thinks they need to be more humble, patient, or respectful. However, what one person calls an upstart, another might call confident or ambitious. Sometimes the established leaders just don't like fresh competition.