SD might refer to:

Arts and entertainment

Businesses and organizations

Places

Science, technology, and mathematics

Electronics and computing

Other uses in science, technology, and mathematics

  • Spasmodic dysphonia, a voice disorder
  • Standard deviation, a mathematical statistical measure
  • Storm Data, an NOAA publication summarising severe weather events in the United States
  • Subdwarf star, a star with luminosity 1.5 to 2 magnitudes lower than that of a main-sequence star of the same spectral type
  • Surface detector, a detector to measure secondary particles of cosmic-ray air showers on ground
  • System dynamics, an approach to understanding the nonlinear behaviour of complex systems over time

Other uses