SDA or sda may refer to:
Science and technology Computing /dev/sda, the first mass-storage disk in Unix-like operating systems T-Mobile SDA, a smartphone Screen Design Aid, a utility program used by midrange IBM computer systems SD Card Association, responsible for Secure Digital memory card standards Serial Data Signal of an I²C electronic bus Slow DoS attack Symbolic data analysis
Life sciences Sabouraud dextrose agar, microbiological media allows fungus to grow SDA (drug), an entactogen drug related to MDA Serotonin–dopamine antagonist, atypical antipsychotic Specific dynamic action, the thermic effect of food Stearidonic acid, omega-3 fatty acid Structured digital abstract, describing relationships between biological entities
Other uses in science and technology Scratch drive actuator, a microelectromechanical device Space domain awareness, the ability to detect, track, and characterize passive and active space objects Stereo Dimensional Array, a Polk Audio technology
Organizations Educational institutions San Dieguito Academy, Encinitas, California, US SDA Bocconi School of Management, in Milan, Italy
Political groups Secular Democratic Alliance (India) Singapore Democratic Alliance Social Democratic Alliance (UK) Social Democratic Alliance in Vietnam South Devon Alliance in England Party of Democratic Action (), a political party in Bosnia and Herzegovina
Other organizations Security & Defence Agenda, a Brussels-based think-tank Seventh-day Adventist Church, a Protestant Christian denomination Shandong Airlines, an airline in China Shop, Distributive and Allied Employees Association, Australia Southern Dames of America, lineage society in the United States Space Development Agency, a US DoD RDT&E agency Systemic Design Association, for systems design Swiss Telegraphic Agency ()
Other uses SDA Tennis Open, a tournament held in Bercuit, Belgium Saddam International Airport, now Baghdad International Airport, airport code SDA Same-day affirmation of financial market deals San Diego and Arizona Railway, reporting mark SDA Severe Disablement Allowance, a UK state benefit Southern Domestic Airspace, Canada Specially denatured alcohol Speed Demos Archive of video game speedruns