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.
The dual number.
Of an item that is one of a pair, the other item in the pair.
Of a regular polyhedron with V vertices and F faces, the regular polyhedron having F vertices and V faces.
To convert from single to dual; specifically, to convert a single-carriageway road to a dual carriageway.
Characterized by having two (usually equivalent) components.
Pertaining to a grammatical number in certain languages that refers to two of something, such as a pair of shoes.
Exhibiting duality.
Being the dual of some other category; containing the same objects but with source and target reversed for all morphisms.
Being the space of all linear functionals of (some other space).
Pertaining to two, pertaining to a pair of.