1. （致词、书信或演出）告别的，告别性质的
A valedictory speech, letter, or performance is one that is intended as a way of saying goodbye when someone leaves another person, a place, or a job.
2. （优秀生在毕业典礼上作的）告别演说
A valedictory is a speech that is given by the student with the highest marks in their class at their graduation ceremony.
1. a farewell oration (especially one delivered during graduation exercises by an outstanding member of a graduating class)