Dual

Dual or Duals may refer to:

==Paired/two things== Dual (mathematics), a notion of paired concepts that mirror one another Dual (category theory), a formalization of mathematical duality see more cases in :Category:Duality (mathematics) Dual number, a number system used in automatic differentiation Dual (grammatical number), a grammatical category used in some languages Dual county, a Gaelic games county which competes in both Gaelic football and hurling Dual diagnosis, a psychiatric diagnosis of co-occurrence of substance abuse and a mental problem Dual fertilization, simultaneous application of a P-type and N-type fertilizer Dual impedance, electrical circuits that are the dual of each other Dual SIM cellphone supporting use of two SIMs Aerochute International Dual a two-seat Australian powered parachute design