Dual

Dual may refer to:

• 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 theories
• Dual (grammatical number), a grammatical category used in some languages
• Duality (electrical circuits)
• 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 (cognitive architecture), an artificial intelligence design model
• DUAL algorithm, or Diffusing update algorithm, used to update Internet protocol routing tables
• DUAL table, a special one-row and one-column database table
• Dual SIM cellphone
• Dual (brand), a manufacturer of Hifi equipment
• Dual county, referring to a Gaelic Athletic Association county which traditionally competes at a similar level in both Gaelic football and hurling