what is the term for someone having lived in three centuries ?

Since there is no documentary evidence to indicate that anyone has ever lived three centuries I don't believe there is a word to names such people.

I suppose you could call someone who lived three hundred years a tri-centenarian, since a person who lives for 100 years is known as a centenarian.

I don't think there's a word for such a thing. The only word I could muster from the latin derivatives would mean they were 300 years old, not living in three centurie.

While this person may also be a supercentenarian, that is not the term you are looking for. A supercentenarian has lived at least 110 years, which could happen over only 2 centuries.

Centenarian is someone who's lived more than 100 years

Super-centenarian is someone who's lived more than 110 years

Not so sure about someone who's lived through three centuries, though =/

@John Clifford - Lol living 108 years is NOT impossible...

Supercentenarians.

Impossibility, would be the technical term.

I guess if we're living in a hypothetical world where people live that long, tricentenarian?

Um...a Centurian maybe? I know of no one who's lived that long.