"large" should be as acceptable as "big". That said, "big" somehow feels better. Wesołych Świąt!
that's what my father called it. my mother said couch. my Aunt Helen, who was from Boston, said "divan".
OK, I guess we can accept "davenport" and "divan". And "couch" was already accepted.
there's also the word Chesterfield, but I think that applies to a specific type of sofa.