What does psi stand for?

Pounds per Square Inch (IDOE)

Pacific Semiconductors, Inc. (MCD)

Pacific Stratus Investigation - Marine science

Pacific Studies Initiative - University of Hawaii, United States (APS)

Pacific Sulfur Investigation - Marine science

Pacific Sulfur/Stratus Investigation (USDC)

Packetnet System Interface

Packetnet Systems Interface

Packet Switching Interface (SAUS)

Packet Switch Interface (SAUS)

Packet System Information

Page Survival Index (PDAA)

Paid Service Indication - Telecommunications (TEL)

Pakistan Standards Institution (IAA)

Palmar Sweat Index (EDAC)

Paper Stock Industries Chapter of ISRI (EA)

Paralog Systems International (IID)

Parameter Setting Instruction (SAUS)

Parameter Signature Identification (SAUS)

Parapat - Sumatra - Seismograph station code, US Geological Survey (SEIS)

Parapsychological Services Institute (EA)

Parapsychology (SAUS)

Parenting Stress Index - Psychology

Partai Socialis Indonesia - Socialist Party of Indonesia

Participation Systems, Inc. - Electronics Communications Co. - Winchester , MA - Telecommunications (TSSD)

Particle-Sizing Interferometer (MCD)

Parti Socialiste Ivoirien - Ivorian Socialist Party - The Ivory Coast - Political party (EY)

Partito Socialista Italiano - Italian Socialist Party - Political party (PPE)

Pasni - Pakistan - Airport symbol (OAG)

Passive Solar Institute - Defunct (EA)

Pathfinder Systems Inc. (SAUS)

Paul Scherrer Institute - Switzerland (BUAC)

Percent Similarity Index

Performance Software, Inc. - Commercial firm

Performance Systems International (SAUS)

Performance Systems International, Inc.

Periodic Somatic Inactivity - Medicine (EDAA)

Peripherally Synapsing Interneuron - Neurology

Peripheral Subsystem Interface - Computer science (IAA)

Permanent Staff Instructor - Military - British

Permuterm Subject Index - Institute for Scientific Information - A publication (IID)

Persist - Telegraphy (PCTE)

Personalised System of Induction (AIE)

Personalized Self-Instruction System - Psychology (QSUL)

Personalized System of Instruction

Personal Security Identifier - Computer science (ELAL)

Personal Sequential-Inference Machine - Computer science

Personal Sequential Interface (SAUS)

Personal Service Income

Personal Style Indicator - Test (TMMY)

Personnel Security Investigation - Military

Personnel Selection Inventory - Test

Person of Special Importance - British military (DMA)

Per Square Inch (ADA)

Petit SystSme Informatique (SAUS)

Petroleum Strategies, Inc. - Commercial firm

Pet Sitters International (NTPA)

Pharmaceutical Society of Ireland (BI)

Pharmaceutical Systems, Inc. - Commercial firm

Phenomenological Systems, Inc.

Photographic Society International (EA)

Photographic Society of Ireland (BI)

Photometric Sunspot Index

Photon Science Instruments (SAUS)

Photo Services Industrial Ltd. - British

PhotoSource International - Commercial firm

Photosystems I - Plant physiology (QSUL)

Physical, Sensitivity, Intellectual - Biorhythmics

Physicians Services Inc. (SAUS)

Physiologic Stability Index - Medicine (EDAA)

Pilot Steering Indicator (SAUS)

Pirates Sick of Initials

Planetary Science Institute (RCD)

Planned Speed Indicator

Planned Start Installation - Telecommunications (TEL)

Plan Shear Indicator (SAUS)

Plan Speed Indicator - Military

Plasma Shadow Inc.

Plas Speed Indicator (IAA)

Platoon Sector Indicator - Army

Play Skills Inventory

Policy Studies Institute - Research center - British (IRC)

Pollutant Standards Index - Environmental Protection Agency

Pollution Standards Index (SARE)

Population Services Inc. (SAUS)

Population Services International (BUAC)

Porta Systems - AMEX symbol

Porta Systems Corp. - AMEX symbol (SPSG)

Positive Self-Image - Psychology

Posterior Sagittal Index - Anatomy (AAMN)

Posterior Superior Iliac Spine - Posterosuperior iliac spine - Anatomy (DAVI)

Postpartum Support, International (EA)

Postscript Interpreter (SAUS)

Post-Tensioning Institute (WPI)

Potential Savings Index (SAUS)

Pound-Force per Square Inch (IAA)

Pounds per Square Inch

Pounds per Square Inch Absolute (IAA)

Power per Square Inch

Power Semiconductors, Inc. (SAUS)

Power Solutions Incorporated

Power Static Inverter (NASA)

Praed Street Irregulars (EA)

Preprogrammed Self-Instruction - Computer science (IEEE)

Preschool Inventory (EDAC)

Pre-Sentence Investigation (OICC)

Present Serviceability Index (IEEE)

Preservice Inspection - Nuclear energy (NRCH)

Pre-Shipment and Inspection (SAUS)

Preshipment Inspection - International trade

President of the Service Institute (SAUS)

Pressure per Square Inch (EEVL)

Pressure Sensitive Identification

Pressurized Sphere Injection (DNAB)

Pressurized Sphere Injector (SAUS)

Presynaptic Inhibition (SAUS)

Prime System Indicator

Private Sector Initiatives (SAUS)

Probe Systems, Inc.

Problem-Solving and Inference Machine (IAA)

Problem Solving Information (SAUS)

Problem-Solving Information - Apparatus

Problem-Solving Interpreter - Computer language

Problem Source Identification

Processor Simulator (SAUS)

Process Safety Information (SAUS)

Process Science Initiative - Manufacturing engineering

Process System Index

Process Systems, Inc.

Process to Support Interoperability (SAUS)

Proctorial System of Instruction (IEEE)

Production Stock Item (MCD)

Product Support Instructions (AAG)

Professional Safety, Inc. - Commercial firm

Professional Secretaries International - Kansas City, MO (EA)

Professional Service Industries, Inc. - Commercial firm

Professional Services Income (WDAA)

Professional Services Index - Medicine (EDAA)

Professional Support, Inc. - Commercial firm

Programmable Series Interface (SAUS)

Programmed School Input (NVT)

Program Status Information - Computer science (MCD)

Program Supply Interest (MCD)

Project Security Instruction (SAUS)

Project Starlight International (EA)

Propulsion System Interface

Prostaglandin Synthetase Inhibition - Medicine (EDAA)

Protosynthetic Indexing (NITA)

Protosynthex Index

Pseudomonas Sp. Lipase

PSI Energy - Associated Press (SAG)

Psychiatric Society for Informatics (SAUS)

Psychological Screening Inventory - Personality development test

Psychological Services, Inc. - Commercial firm

Psychological Society of Ireland (BUAC)

Psychosomatic Inventory - Psychology

Publications Standing Instruction (AAG)

Public Services International - See also ISP - Ferney Voltaire, France (EAIO)

Pulsepower Systems Incorporated

Pulse Sciences, Inc.