étage

Étages is a French noun that denotes a level or floor in a building, as well as a stage in a sequence. In everyday language, it is most commonly used to refer to the horizontal divisions of a multi-storey structure.

In architecture and construction, an étage corresponds to a distinct horizontal level that can house rooms or offices. The ground level is typically called the rez-de-chaussée, while the floors above are numbered as premier étage (first floor), deuxième étage (second floor), and so on. The term is also used in building plans, real estate descriptions, and navigation within a building, such as “à l’étage” or “cet étage est réservé à...” It can indicate both inhabited and non-habitable levels.

In other technical contexts, étage is used to describe stages of a system. In rocketry and aerospace, an étage refers to a self-contained propulsion section that can detach from the vehicle after its mission is completed, forming a multi-stage launch configuration.

In science, étage has specialized uses as well. In geology and paleontology, it is a stratigraphic unit roughly equivalent to the English term stage, defining a rock interval and its corresponding time frame based on fossil content and characteristics. In ecology and forestry, the term describes vertical stratification, the different layers of vegetation within a forest, such as canopy, understory, and forest floor, each forming an étage of the ecosystem.