Which term describes a stair that is not enclosed by walls?

The term "open" accurately describes a stair that is not enclosed by walls. Open staircases feature balustrades or railings on the sides, allowing for unobstructed views and access, contributing to an airy and spacious environment within a structure. This design is not only visually appealing but also enhances safety by providing a clear line of sight.

In contrast, closed stairs typically have walls on both sides, which can create a more confined feel and limit visibility. The term "light" does not specifically relate to the enclosure of a stair, and "wall-mounted" refers to a different concept entirely, often associated with shelving or cabinets that are attached directly to a wall rather than a stair configuration. Thus, the term "open" is the most precise descriptor for a staircase lacking enclosure by walls.