(mathematics) Either of a pair of polyhedra in which the faces of one are equivalent to the vertices of the other.

plural of dual polyhedron

Either of two modes in which a device is designed to operate

plural of dual mode

plural of dual space

Alternative form of dual SIM

(mobile telephony) holding two SIM cards

(grammar) A grammatical number denoting a quantity of exactly two.

(uncountable) The control of a vehicle by either one of two people / (countable) The equipment that allows such control

plural of dual control