- An example of something dual is an electric toothbrush that both rotates and moves from side-to-side while it brushes your teeth; dual movement.
- An example of something dual is a plan of attack that has two parts; dual plan of attack.
- of two
- having or composed of two parts or kinds, like or unlike; double; twofold: a dual nature
Origin of dualClassical Latin dualis ; from duo, two
- dual number
- a word having dual number
- Composed of two usually like or complementary parts; double: dual controls for pilot and copilot; a car with dual exhaust pipes.
- Having a double character or purpose: a belief in the dual nature of reality.
- Grammar Of, relating to, or being a number category that indicates two persons or things, as in Greek, Sanskrit, and Old English.
- The dual number.
- An inflected form of a noun, adjective, pronoun, or verb used with two items or people.
Origin of dualLatin dualis, from duo, two; see dwo- in Indo-European roots.
- Exhibiting duality; characterized by having two (usually equivalent) components.
- Acting as a counterpart.
- dual-headed computer
- (grammar) Pertaining to grammatical number (as in singular and plural), referring to two of something, such as a pair of shoes, in the context of the singular, plural and in some languages, trial grammatical number. Modern Arabic displays a dual number, as did Homeric Greek.
- (linear algebra)
- (category theory)
- Of an item that is one of a pair, the other item in the pair.
- (geometry) Of a regular polyhedron with V vertices and F faces, the regular polyhedron having F vertices and V faces.
- The octahedron is the dual of the cube.
- (grammar) dual number The grammatical number of a noun marking two of something (as in singular, dual, plural), sometimes referring to two of anything (a couple of, exactly two of), or a chirality-marked pair (as in left and right, as with gloves or shoes) or in some languages as a discourse marker, "between you and me". A few languages display trial number.
- (mathematics) Of a vector in an inner product space, the linear functional corresponding to taking the inner product with that vector. The set of all duals is a vector space called the dual space.