valedictorian

noun

1. a student, usually the one ranking highest academically in a school graduating class, who delivers the valedictory at the commencement exercises.

adjective also: valedictory

1. saying goodbye
2. of or relating to a farewell or an occasion of farewell

noun

3. US and Canadian a person, usually the most outstanding graduate, who delivers a farewell speech at a graduation ceremony

1832 (n.), 1834 (adj.), American English, from valedictory + -ian.