1. A certificate that has been given by a school, college, or university which verifies that someone has completed a certain course of study or has graduated after a certain amount of education: After going to high school and finishing all of the required subjects with good grades, Jackie received her high school diploma and now she can apply for admission to the nearby college.
2. A document that grants certain rights, privileges, honors, etc.: A diploma, or certificate, signed by a king in historical contexts, verified a grant or tenure of a defined piece of land and its conditions.
3. Etymology: from Greek > Latin diploma, "paper folded double".