Other forms: reformedly
Someone who's reformed is changed in a positive way. A reformed bully has stopped shoving smaller kids around and makes a point of treating everyone kindly.
A reformed prison system would be one that has eliminated controversial punishments like solitary confinement, and a reformed group of military rebels might form a peaceful political party. Sometimes you'll see this adjective in a religious context — for example, Calvinism is known as "Reformed Christianity," a reference to the Protestant Reformation. The Latin root, reformare, means "change."