Dual - Definition and Overview

A dual is a pair – a grouping of two. The word duality has a variety of different meanings in different contexts:

In the religion of the Moche of Peru and the Chinese of China, duality is the premise that everything has an opposing force that must be, or will be in balance. See Ying|Yang.
In physics, duality is present when two different models actually turn out to be equivalent. See duality (physics), wave-particle duality.
Duality (projective geometry).
A variety of different kinds of duality occurring in mathematics are listed at duality (mathematics).
In analytical psychology, duality is an archetype, that is to say, one of the deep powerful symbols of the functioning of the psyche.
In alchemy, duality is a dynamic principle of opposing or complementary elements or spirits.
Duality is an album of Lisa Gerrard and Pieter Bourke.
In some languages, in addition to the singular and plural numbers there is also a dual number, which is used when exactly two people or things are meant. This is known as the dual grammatical number.
Dual is a brand name for Hifi equipment, mostly known for vinyl record players.
In electronics, duality is the relationship between two devices or circuits that have mathematical descriptions that are identical except that voltages in one correspond to currents in the other, and vice versa. See dual (electronics).
Dual! is the name of an anime series, Dual! Parallel Trouble Adventure
A simultaneous application of a P type and N type fertilizer