Mathematical concepts

thumb|upright=1.2|From left to right: a square (geometry)|square, a [[cube and a tesseract. The square is two-dimensional (2D) and bounded by one-dimensional line segments; the cube is three-dimensional (3D) and bounded by two-dimensional squares; the tesseract is four-dimensional (4D) and bounded by three-dimensional cubes. ]] [[File:Dimension levels.svg|thumb|upright=1.2| The first four spatial dimensions, represented in a two-dimensional picture.

abstract object in mathematics

unit of angle

limiting case in which an element of a class of objects is qualitatively different from the rest of the class

undefined term motivated informally, usually by an appeal to intuition and everyday experience, or introduced axiomatically and eventually generated only by a series of elementary operations

lack of interruption or disconnection; the quality of being continuous in space or time

gradual quantitative transition without abrupt change

ratio of the circumference of a circle to its radius