View source for SD

{{pp-protected|reason=Persistent [[WP:Disruptive editing|disruptive editing]]; requested at [[WP:RfPP]]|small=yes}}
{{wiktionary|sd|SD|s.d.}}
'''SD''' may refer to:
{{TOC right}}
== Military and weaponry ==
* [[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

== Organisations ==
=== Political parties ===
* [[Democratic Left (Italy)]] (2007–2010; {{langx|it|Sinistra Democratica|links=no}})
* [[Social Democrats (Slovenia)]] (founded 1993)
* [[Solidarity (Brazil)]] (founded 2012)
* [[Democratic Party (Poland)]] (founded 1937; {{langx|pl|Stronnictwo Demokratyczne|links=no}}) 
* [[Sweden Democrats]] (founded 1988)
* [[Swiss Democrats]], Switzerland (renamed 1990; {{langx|de|Schweizer Demokraten|links=no}})
* [[Serbian Right]] (founded 2018; {{langx|sr-Latn|Srpska desnica|links=no}})

=== Other organisations ===
* ''[[Sicherheitsdienst]]'', Nazi intelligence service (1931–1945)
* [[Sisters of the Destitute]], a Syro-Malabar Catholic order (founded 1927)
* [[Sudan Airways]] (founded 1946; IATA:<code>SD</code>)

==Places==
* [[Sudan]] (ISO 3166 country code:<code>SD</code>)
* A common abbreviation for the U.S. city of [[San Diego|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)

==Science and technology==
===Astronomy===
* [[Subdwarf]], a class of star
* Surface detector, of cosmic rays at the [[Pierre Auger Observatory#Surface detector (SD)|Pierre Auger Observatory]] 

===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
* [[Stable Diffusion]], a text-to-image generator

===Mathematics===
* [[sd (elliptic function)]], one of Jacobi's elliptic functions
* [[Standard deviation]] (SD), a statistical measure of variation

===Medicine===
* [[Spasmodic dysphonia]], a voice disorder
* Stable disease, a [[RECIST]] chemotherapy outcome

=== Other uses in science and technology ===
* [[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

==Other uses==
* ''[[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)

==See also==
* [[SD1 (disambiguation)]]

{{disambiguation}}