SAD

The initialism SAD may refer to:

Medicine

 * Schizoaffective disorder, a psychiatric diagnosis
 * Social anxiety disorder
 * Seasonal affective disorder, typically winter depression
 * Separation anxiety disorder in children
 * Sagittal abdominal diameter, body diameter at the waistline

Political or military

 * Shiromani Akali Dal, a political party in India
 * Special Activities Division of the US Central Intelligence Agency, now named the Special Activities Center
 * Saraya Awliya al-Dam, an Iraqi militia

Sports clubs

 * Sociedad Anónima Deportiva, a type of incorporated sports club in Spain
 * Sociedade Anónima Desportiva, a type of incorporated sports club in Portugal

Science and technology

 * Selected area diffraction, a crystallographic experimental technique
 * Sum of absolute differences, in digital image processing
 * Single-wavelength anomalous dispersion, in X-ray crystallography

Transportation

 * Sandwell & Dudley railway station, with the station code SAD
 * Safford Regional Airport, Arizona, US, with the IATA airport code SAD

Songs

 * "S.A.D.", from Man Overboard's 2013 album Heart Attack

Other uses

 * SAD scheme, a form of intellectual property enforcement in the United States
 * Singles Awareness Day, a humorous holiday every February 14
 * The Single Administrative Document, EU customs form
 * The Standard American Diet, another name for the Western pattern diet
 * The Suicide Attack Database, now named the Database on Suicide Attacks