planeerne

Planeerne is a term found mainly in Danish-language texts as the definite plural form of the borrowed English word plane. It does not denote a single, widely recognized concept in English-language sources, and its meaning depends on the context. In mathematics, the underlying idea is a plane—a flat, two-dimensional surface that extends indefinitely. In three-dimensional space, planes can be described by a point and a normal vector, by three non-collinear points, or by a linear equation. When Danish writers use planeerne, they typically refer to several such surfaces discussed together, i.e., the planes in question.

In other contexts, planeerne may simply reflect the use of the English term "plane" in technical or educational writing, with the definite plural signifying multiple planar surfaces, layers, or facets in design, architecture, or manufacturing. Because "plane" also appears as a woodworking tool, the exact meaning of planeerne is usually clarified by nearby words that indicate whether the reference is to geometric planes or to planar tools.

In sum, planeerne serves as a language-specific plural form indicating multiple planes within a discourse, rather than constituting a distinct scientific concept on its own.