From Longman Dictionary of Contemporary Englishldoce_315_bstaircasestair‧case /ˈsteəkeɪs $ ˈster-/ ●●○ noun [countable] 
DHHTBBa set of stairs inside a building with its supports and the side parts that you hold on to
DHHTBBa set of stairs inside a building with its supports and the side parts that you hold on toExamples from the Corpus
staircase• A small lamp was mounted on an upright stanchion near the head of each staircase.• She shook herself slightly and took a final look down the proud granite staircase towards the traffic.• After the appropriate phone call, I am ask d to walk down an oak spiral staircase one floor.• She pulled herself back up the spiral staircase and made for the bathroom.• Adam didn't move until he was sure he could no longer hear her penetrating voice echoing on the staircase.• The staircase beckoned up a modest rise, then disappeared around a bend.• It led to a five-foot-wide walnut staircase that swept up in a sumptuous curve to the floor above.• At each end of the second floor of these dwellings typically were staircases, one for men and one for women. 