Valedictory:
relating to saying goodbye, especially formally [Cambridge Dictionary]
I would have thought I’d know valedictory at this point, but no. Interesting. Noted in “McCarthy became the latest victim of Trump’s extreme GOP revolution,” Stephen Collinson, CNN/Politics:
“I don’t regret standing up for choosing governance over grievance,” McCarthy said, putting a brave face on his humiliation in a valedictory news conference that capped a speakership that had always seemed to be on a short-term lease.
