A progressive is one who is dedicated to progress. Progress consists in advancing our standing as citizens under our living Constitution. It allows us to be free in our persons while still being bound by law. It proclaims that we must strive to form a more perfect union, promote justice, provide for the common defense, and secure the blessings of liberty to our progeny and ourselves. This means that we, the people, must do all these things, not as isolated individuals, but as held together by a common bond, with an eye to our past but always looking to the future.

Keywords from above, used in other answers: