MDD

MDD may refer to:

• Major depressive disorder, a mental disorder involving persistent low mood, low self-esteem and loss of interest. It is also known as clinical depression.
• Mate-Demate Device, a specialized crane used to piggyback the Space Shuttle onto an airplane
• Mammal Diversity Database, online checklist of mammal species maintained by the American Society of Mammalogists
• Medical Devices Directive
• Mernda railway station, Melbourne
• Midland Airpark (IATA: MDD), a public use airport in Midland, Texas
• Mine detection dogs
• Ministry of Defence (Italy), known natively as Ministero della Difesa
• Mirrored Drive Door, a case design for the Power Mac G4
• Model-driven development, a software engineering discipline
• Movement for Direct Democracy, defunct Venezuelan political party.