PSD

PSD may refer to:

Science and engineering

• Particle size distribution
• Phase sensitive detector
• Phase space density, number of particles (atoms) populating the same state. Important in Bose Einstein Condensation
• Proportional/Sum/Derivative, a version of the common discrete controller Proportional/Integral/Derivative
• Platform screen doors, doors used to prevent people from falling off railway platforms
• Position sensitive device and/or position sensitive detector, that can measure a position of a light spot in one or two-dimensions on a sensor surface.
• Positive-semi-definiteness as it relates to matrices
• Postsynaptic density, a specialization of the cytoskeleton at the synaptic junction
• Power Spectral Density, the power of a signal per some unit of measurement such as temporal or spatial frequency used in signal analysis, and other physical phenomena, such as Continuous Gust analysis.
• Programmable system device, type/brand of microprocessor companion chips, manufactured by STMicroelectronics
• Photosensitizer Database, a database containing photosensitizers and their related information manually collected from literatures

Computers

• A portable or personal storage device, small hard disks designed to copy digital photographs from a camera
• .psd (Photoshop document), the default file extension of the proprietary file format of Adobe System's Photoshop program.
• Pose Space Deformation, a computer character animation technique
• Professional Scrum Developer, a course leading to certification for Scrum (development)
• Programmable system device, an integrated circuit manufactured by STMicroelectronics and including Flash-ROM, RAM, and logic functions on a single chip
• Program structure diagram, also known as a Nassi–Shneiderman diagram

Medicine/Psychology

• Postsynaptic density, a protein dense specialization attached to the postsynaptic membrane
• Post-traumatic stress disorder (more commonly abbreviated PTSD)
• Protein S deficiency, a blood disorder associated with increased risk of venous thrombosis

Politics

• Parti social démocratique du Québec, a former provincial political party in Quebec, Canada
• Party of Socialists and Democrats, a major political party of San Marino
• Civil Movement "People's Self-Defense", a defunct political movement in Ukraine which was part of the Our Ukraine–People's Self-Defense Bloc electoral alliance
• Social Democratic Party (Albania), a minor political party of Albania
• Social Democratic Party (Angola), a political party of Angola
• Social Democratic Party (Benin), a political party of Benin
• Social Democratic Party (Brazil, 1945-65), a defunct political party of Brazil
• Social Democratic Party (Brazil, 2011), a current political party of Brazil
• Social Democratic Party (El Salvador), a political party of El Salvador
• Social Democratic Party (France), a defunct political party of France
• Social Democratic Party (Mexico), a defunct political party of Mexico
• Social Democratic Party (Moldova), a political party of Moldova
• Social Democratic Party (Nicaragua), a political party of Nicaragua
• Social Democratic Party (Portugal), a major political party of Portugal
• Social Democratic Party (Romania), a major political party of Romania
• Social Democratic Party (Rwanda), a political party of Rwanda
• Social Democratic Party (Spain), a defunct political party of Spain
• Social Democratic Party (India), a political party of India
• Socialist Destourian Party, the old name (to 1988) of the ruling party in Tunisia, currently called Constitutional Democratic Rally

A .PSD file is a layered image file used in Adobe PhotoShop. PSD, which stands for Photoshop Document, is the default format that Photoshop uses for saving data. PSD is a proprietary file that allows the user to work with the images’ individual layers even after the file has been saved.

Finance

• Payment Services Directive, an initiative to regulate payment services and payment service providers in the European Union
• Private Sector Development, a strategy for promoting economic growth and reducing poverty in developing countries

Travel

• IATA code for Port Said Airport, Port Said, Egypt

People

• PSD (rapper), a Californian rapper and hip-hop producer.
• Perri Shakes-Drayton, British 400m runner

Education

• Pennridge School District, a school district in Pennsylvania, near Philadelphia
• Philippine School Doha, a Filipino school in Doha, Qatar
• Pontiac School District, a school district in Michigan, near Detroit
• Poudre School District, a school district in Larimer County, Colorado

Others

• Pennsylvania Sumerian Dictionary
• Personal Security Detachment, U.S. Army unit assigned to protect VIPs
• Personal Security Detail or Protective Services Detail Military, or private security contractor unit tasked to protect a client
• Pesticides Safety Directorate, UK
• Plains Indian Sign Language, an endangered native sign language of North America
• Plastic Surgery Disasters, a 1982 album by the Dead Kennedys
• Power Split Device, part of the Hybrid Synergy Drive on a Toyota Prius
• Ford Power Stroke engine, the Ford turbo diesel engine available in the F250 / F350 line as well as other trucks
• Prevention of Significant Deterioration of Air Quality
• Program Service Data, also known as program-associated data, usually data sent along with an HD radio program
• Public Safety Dispatcher, also known as emergency dispatchers, Telecommunicators or 9-1-1 dispatchers