Meaning of STAIRCASE in English
[noun] [C] - a set of stairs inside a building which usually has a bar fixed on the wall or onto vertical poles at the side for you to hold on toThe staircase was lined with paintings of his ancestors.She descended the sweeping (= long and wide) staircase into the crowd of photographers and journalists.The apartment is on two floors and has a spiral staircase (= stairs curved around a central point) linking both levels.
Cambridge English vocab. Кембриджский английский словарь. 2012