Apimtis

Apimtis is a term used in Lithuanian to denote the length of the boundary of a two‑dimensional figure, commonly translated as perimeter. In broader usage, apimtis can also mean the scope, extent, or reach of something. In geometry, the word is typically applied to planar shapes or regions and is distinguished from area, which measures size rather than boundary length.

In mathematical terms, the apimtis of a polygon is the sum of the lengths of its sides. For a circle, the apimtis is the circumference, given by the formulas 2πr, where r is the radius, or πd, where d is the diameter. The apimtis is thus a one‑dimensional measure of a region’s boundary, not a measure of its interior.

Examples include: a rectangle with sides a and b has apimtis 2(a + b); an equilateral triangle with side length s has apimtis 3s; a circle of radius r has apimtis 2πr. For irregular shapes, the apimtis is found by summing the boundary segments or by integrating along the boundary.

Relation to other concepts: apimtis is related to, but distinct from, area; two figures can share an apimtis while having different areas. In applied contexts, apimtis appears in fields such as architecture, land surveying, and computer graphics when boundary length is relevant.

Etymology: the term is built from Lithuanian morphemes associated with surrounding or enclosing, reflecting its geometric meaning of the boundary that surrounds a figure.