SD

SD may refer to:

Organisations

• Sicherheitsdienst (Security Service), the intelligence service of the Nazi SS
• Sinistra Democratica (Democratic Left), an Italian political party
• Sisters of the Destitute, a Syro-Malabar Catholic women's order
• Social Democrats (Slovenia), a left-wing Slovenian political party
• Democratic Party (Poland) (Stronnictwo Demokratyczne), a defunct Polish party
• Sudan Airways (IATA airline designator: SD)
• Sweden Democrats, a right wing party in Sweden
• Swiss Democrats or Schweizer Demokraten, a right-wing political party in Switzerland

Places

• San Diego, California
• Shandong, a province of China (Guobiao abbreviation: SD)
• South Dakota (US postal abbreviation)
• Sudan (ISO country code SD)
• Eswatini (formerly Swaziland), vehicle registration code SD

Science and technology

• Spasmodic dysphonia, a voice disorder
• Storm Data, US NOAA publication
• Subdwarf star
• Surface detector, of cosmic rays at the Pierre Auger Observatory
• System dynamics, understanding nonlinear systems
• Service design, the holistic design of end-to-end service experiences
• Stable disease, a possible outcome of chemotherapy according to the RECIST classification

Electronics and computing

• 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

Mathematics

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

Other uses

• Sekolah Dasar, term for primary school in Indonesia
• Super deformed, an art style
• Sindhi language (ISO 639-1 code: sd)
• Southern Cross Decoration (SD), a South African military award
• sine die, Latin, undated (literally without a day)

See also

• SD1 (disambiguation)