SD is an acronym that may mean:

• Sales & Distribution (business)
• San Diego, a U.S. city
• Secure Digital memory card
• Sicherheitsdienst (German)
  • security firm
  • Security Police, the intelligence service of the Nazi SS
• SmackDown!, a U.S. professional wrestling television program
• South Dakota, a U.S. state
• Standard Deviation (statistics)
• Sudan (ISO country code)
• Sudan Airways (IATA airline designator)
• Super Deformed, an exaggerated drawing style used in anime and manga
• Super Dollfie, a strung, ball-jointed doll by Japanese company Volks
• Sustainable development