valedictory

Of or pertaining to a valediction (“an act of parting company; a speech made when parting company”); designed for or suitable to an occasion of bidding farewell or parting company.

a valedictory oration

Supp'd at Mr. Edwᵈ Sheldon's, where was Mr. [John] Dryden the Poet, who now intended to write no more Plays, being intent on his Translation of Virgil. He read to us his Prologue and Epilogue to his valedictory Play, now shortly to be acted.

Of or pertaining to a valedictorian (“the individual in a graduating class who delivers the farewell address, often the person who graduates with the highest grades”).

The first was Larissa Martinez, who divulged her undocumented status during her valedictory speech and told the crowd at her McKinney, Texas, high school graduation she would be attending Yale University with a financial aid package in the fall.

An address given on an occasion of bidding farewell or parting company.

[Jean-Claude] Juncker gave an emotional valedictory. When he stopped speaking, an Italian journalist stood up. "History will judge you, Mr Juncker," the journalist said solemnly, "but we will never forget you" before urging a round of applause for the Luxembourger's "30 years as a true European".

A speech given by a valedictorian at a commencement or graduation ceremony.