LDA may refer to:

Aviation

• Localizer type directional aid, an instrument approach to an airport
• Landing distance available, the length of runway that is available for the ground run of an airplane landing

Law

• Legal document assistant, a non-lawyer authorized to assist with the preparation of legal instruments
• Lobbying Disclosure Act of 1995, legislation in the United States
• Legal drinking age, the minimum age at which one can legally consume alcohol

Medicine

• Left-displaced abomasum, condition of ruminants
• Low dose allergens, a variant of enzyme potentiated desensitization

Science and technology

• Laser Doppler anemometry, technique to measure velocity
• Latent Dirichlet allocation, a generative statistical model
• Linear diode array, used for digitizing x-ray images
• Linear discriminant analysis, a type of statistical analysis
• Lithium diisopropylamide, a strong base in chemistry
• Local delivery agent, software that delivers e-mail messages
• Local-density approximation, in quantum-mechanical density functional theory
• Low density amorphous ice, an amorphous solid form of water
• Lobate debris apron, a type of geologic feature observed on Mars

Organizations

• Lahore Development Authority, agency in Lahore, Pakistan
• Liga Deportiva Alajuelense, a Costa Rican football club
• London Democratic Association, 19th century organisation in England
• London Development Agency, regional development agency for the London region in England
• Lord's Day Alliance, an ecumenical Christian first-day Sabbatarian organization

Other uses

• LDA (singer)
• Little Dark Age, a 2018 studio album by MGMT