Simple past tense and past participle of footnote.(verb)
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Use "footnoted" in a sentence
"The book is heavily footnoted, which is definitely a plus."
"The "gen kill" reference wasn't something I footnoted, which is my bad."
"Near the end of his call, he "footnoted" his remarks with, and I'm quoting as nearly as I can, "Now, I love Premier Williams as much as the next person, but...""