2ulotteinen

2ulotteinen (two-dimensional) describes objects, spaces, or representations that have two spatial dimensions only: length and width. In mathematics and related disciplines, two-dimensionality is contrasted with one-dimensional (lines) and three-dimensional (space). The term is commonly used in Finnish contexts as well as in international discussions, often alongside the abbreviation 2D.

Mathematically, the standard model of a two-dimensional space is the Cartesian plane R2, consisting of all ordered pairs (x, y) of real numbers. A point is defined by two coordinates, and basic figures such as lines, curves, and polygons exist within this plane. Distances are given by the Euclidean metric d((x1, y1), (x2, y2)) = sqrt((x1 − x2)^2 + (y1 − y2)^2), and area is computed with the usual formulas or double integrals. The plane has two basis directions, typically denoted e1 and e2, representing the two independent axes.

In applications, 2D is common in computer graphics, image processing, and cartography, where scenes and maps are represented on a flat plane. Two-dimensional models are used to plan layouts, designs, and user interfaces, and many three-dimensional objects are often projected onto 2D planes for visualization, printing, or rendering. The concept also appears in geometry, physics of surfaces, and various engineering disciplines.

Finnish terminology for the concept is typically kaksulotteinen or kaksiulotteinen; the form 2-ulotteinen or 2ulotteinen is used in technical contexts. The abbreviation 2D is widely used in English-language sources and international mathematics and computer science.