palier

Palier is a French noun with several related senses. In architecture and construction, a palier is a flat, level space between two flights of stairs, or the landing at the top or bottom of a staircase. It provides a resting point and a transition from one flight to another, and its shape and finish typically match the surrounding floor or corridor.

In mechanical engineering, palier denotes a bearing—the component that supports a rotating shaft and allows it to turn with minimal friction. Palieres can be plain bearings (palier lisse) or rolling-element bearings such as ball bearings (palier à billes) and roller bearings (palier à rouleaux). They are lubricated to reduce wear and accommodate radial and/or axial loads, depending on the design.

Beyond its technical senses, palier can also be used figuratively to mean a threshold or milestone, a level that marks a transition or a point to be reached. For example, one might speak of reaching a growth palier or crossing a performance palier, in reference to a new stage or standard.

Etymology traces palier to French usage tied to stair landings; over time the term broadened to refer to similar transitional surfaces in architecture and to bearing components in machinery. In modern usage, the word appears across architecture, engineering, and everyday language to denote either a physical flat platform or a supporting, rotating element, as well as a figurative threshold.