Definition:Regular


 * Set Theory:
 * Regular Cardinal


 * Matrix Algebra:
 * Regular Matrix: another term for an invertible matrix


 * Abstract Algebra:
 * Regular Representations:
 * Left Regular Representation
 * Right Regular Representation
 * Regular Element: another term for a cancellable element
 * Regular Element of Ring: an element of a ring which is not a zero divisor


 * Geometry:
 * Regular Polygon, for example:
 * Regular Pentagon
 * Regular Hexagon
 * Regular Polyhedron: also see: Platonic Solid


 * Topology:
 * Regular Open Set
 * Regular Closed Set
 * Regular Value
 * Regular Space:
 * also see $T_3$ space (beware: in some treatments the definitions of these are reversed)
 * Completely Regular Space, also known as a Tychonoff Space:
 * also see $T_{3 \frac 1 2}$ space (beware: in some treatments the definitions of these are reversed)


 * Number Theory:
 * Regular Continued Fraction: a continued fraction in canonical form


 * Graph Theory:
 * Regular Graph


 * Formal Systems:
 * Regular Expression

Also see

 * Definition:Singular
 * Definition:Canonical

Natural Language
The mathematical meaning of regular evolves from its natural language usage to mean obeying rules, uniform, occurring at equal time intervals or according to a common pattern, and therefore predictable.

Its linguistic origin is from the Latin rēgulāris, meaning guided by a rule or rules.

This ultimately originates from Proto-Indo-European reg-, meaning to move in a straight line.