"He never called me 'boy,' he always called me 'son,'" he said referring to one of the southern Democrats at a fundraising event on Tuesday night.
His comments were quickly panned by rival candidates and critics who noted the racial undertones of the comment.
...Speaking at the Carlyle Hotel in New York City on Tuesday night, Mr Biden praised the "civility" amongst lawmakers in the 1970s when he first joined the US Senate.
He called out his work with two southern Democrats who used their political position to advance their beliefs that white and black people should not live together.
"I was in a caucus with James O Eastland," Mr Biden told the audience, referring to the segregationist senator from Mississippi.
He added that Eastland never referred to him as "boy" during their working relationship.
The Washington Post, and other outlets, have pointed out that "boy" is a racial epithet used to describe black men. Mr Biden's campaign have yet to comment on why it would be unusual for the former senator to not call Mr Biden - who is white - "boy".
...Mr Eastland notably referred to African Americans as an "inferior race" and warned that racial integration would lead to "mongrelisation".
Referring to late Georgia Senator Herman E Talmadge - who opposed the desegregation of US public schools, Mr Biden said: "We got things done. We didn't agree on much of anything. We got things done."...