SD

SD may refer to:

• Smith & Wesson SD, a line of pistol (first made 2010)
• SD radar, an early US Navy radar system
• Southern Cross Decoration (SD), a South African military award

• Democratic Left (Italy) (2007–2010; Italian: Sinistra Democratica)
• Social Democrats (Slovenia) (founded 1993)
• Solidarity (Brazil) (founded 2012)
• Democratic Party (Poland) (founded 1937; Polish: Stronnictwo Demokratyczne)
• Sweden Democrats (founded 1988)
• Swiss Democrats, Switzerland (renamed 1990; German: Schweizer Demokraten)
• Serbian Right (founded 2018; Serbian: Srpska desnica)

• Sicherheitsdienst, Nazi intelligence service (1931–1945)
• Sisters of the Destitute, a Syro-Malabar Catholic order (founded 1927)
• Sudan Airways (founded 1946; IATA:SD)

• Sudan (ISO 3166 country code:SD)
• A common abbreviation for the U.S. city of San Diego, California and the San Diego Padres—the city's Major League Baseball team
• Shandong, a province of China
• South Dakota, a US state
• Eswatini (formerly Swaziland; SD on vehicle plates)

• Subdwarf, a class of star
• Surface detector, of cosmic rays at the Pierre Auger Observatory

• SD card (Secure Digital), a flash memory card format
• Software Distributor, an HP-UX system
• Standard-definition television
• Super Density Disc, an optical disc format
• Stable Diffusion, a text-to-image generator

• sd (elliptic function), one of Jacobi's elliptic functions
• Standard deviation (SD), a statistical measure of variation

• Spasmodic dysphonia, a voice disorder
• Stable disease, a RECIST chemotherapy outcome

• Service design, holistic design of service experience
• Spiral Dynamics, a model of individual and societal development
• Storm Data, a US meteorological journal
• System dynamics, of nonlinear systems

• Sekolah Dasar, term for primary school in Indonesia
• Super D (cycling), a class of mountain bike race
• Super deformed, an art style
• Sindhi language (ISO 639-1 code: sd)
• sine die, Latin, undated (literally without a day)

• SD1 (disambiguation)