There is no "definition" ... However, my understanding is that while conservatism emphasizes preserving traditions and existing institutions, and classic liberalism emphasizes individual freedom and minimal government intervention, progressivism focuses on using collective actions and political reforms to fix structural inequities.

I found this quote that resonates with me: "The country will not be a good place for any of us to live in unless we make it a good place for all of us to live in." - Theodore Roosevelt