President Biden answers the (self-asked) question by starting an anecdote about talking to Xi Jinping on the subject. He briefly gets tongued-tied while trying to say "I was in the foothills of the Himalayas", but goes on to finish the story and give the word "possibilities" as the answer to the question.
Original footage
The White House provided a transcript of the speech:
And, folks — (applause) — let me close with what I’ve long said: America is a nation that can be defined in a single word. I was in the foothi- — foot- — excuse me, in the foothills of the Himalayas with Xi Jinping, traveling with him. (Inaudible) traveled 17,000 miles when I was Vice President at the time. I don’t know that for a fact.
And we were sitting alone. I had an interpreter and he had an interpreter. And he looked at me. In all seriousness, he said, “Can you define America for me?” And I said what many of you heard me say for a long time. I said, “Yes, I can, in one word: possibilities.” (Applause.) “Possibilities.” That, in America, everyone should be able to go as far as their hard work and God-given talent will take them. And possibilities. We’re the only ones. That’s why we’re viewed as the “ugly Americans”: We think anything is possible. (Laughter.)
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