While these four words all refer to a set of steps connecting different levels, each has a different focus. 'Stairs' is by far the most common everyday word — people naturally say 'I ran up the stairs' or 'the stairs creaked at night.' 'Stairway' places the emphasis on the passage or route, and is often used in public or larger contexts ('a grand stairway in the opera house,' 'the emergency stairway at the back of the store'). 'Staircase' draws attention to the structure itself, including handrails, banisters, and sometimes decoration, so it often describes a more finished or impressive feature ('the hotel's marble staircase had carved wooden banisters'). 'Stairwell' is narrower and refers specifically to the enclosed vertical shaft that contains the stairs, common in multi-story office buildings. For example: 'She took the stairs instead of the elevator' (everyday action), 'The museum's spiral staircase was a work of art' (structural description), and 'Smoke detectors went off in the stairwell during the drill' (enclosed space).
Formed by combining 'stair' (from Old English 'stǣġer,' meaning a step or a flight of steps) and 'way' (from Old English 'weg,' meaning a path or route). The compound 'stairway' has been used since the 1500s to describe a path made of steps that connects different levels of a building.