Companies and organizations

• Electro Scientific Industries
  Electro Scientific Industries
  Electro Scientific Industries, Inc. is a high technology company headquartered in the Portland, Oregon metropolitan area, more specifically in Washington County, in the unincorporated Cedar Mill area north of Beaverton, U.S.A. It is a pioneer developer, and leading supplier, of photonic and...
  
   (ESI; Nasdaq: ESIO), a high-technology company based in Oregon, United States
• Employees’ State Insurance scheme, the national health and disability insurance for industry workers and other employees in India
• Erwin Schrödinger Institute for Mathematical Physics, an Austrian research institute
• ESI International
  ESI International
  ESI International, Inc. is a provider of learning-based solutions focused on skills training and consulting in project management, program management, business analysis, business skills and contract management....
  
  , formerly Educational Services Institute, a workforce training firm based in Virginia, United States
• European Software Institute
  European Software Institute
  European Software Institute is a non-profit private technological center launched as an initiative of the European Commission, with the support of the Basque Government and leading European companies working in the Information Technology field....
  
  , a non-profit foundation launched as an initiative of the European Commission
• Express Scripts Incorporated
  Express Scripts Incorporated
  Express Scripts, Inc. is a Fortune 100 company headquartered in Cool Valley, Missouri. It began in 1986 in St. Louis, Missouri as a result of a joint venture between a retail chain of more than 79 pharmacies and Sanus Corp. Health Systems. Express Scripts was purchased by New York Life Insurance...
  
  , a pharmacy benefit manager

Computer science

• Edge Side Includes
  Edge Side Includes
  Edge Side Includes or ESI is a small markup language for edge level dynamic web content assembly. The purpose of ESI is to tackle the problem of web infrastructure scaling. It is an application of edge computing....
  
  , a markup language for edge level dynamic web content assembly
• Electronically Stored Information
  Electronically stored information
  Electronically stored information, for the purpose of the Federal Rules of Civil Procedure is information created, manipulated, communicated, stored, and best utilized in digital form, requiring the use of computer hardware and software....
  
  
• Enclosure Services Interface
  Enclosure Services Interface
  The Enclosure Services Interface is a computer protocol used in SCSI enclosures. This is part of a chain of connections that allows a host computer to communicate with the enclosure to access its power, cooling, and other non-data characteristics...
  
  , a computer protocol used in SCSI enclosures
• Extended Source Index (a register in the x86 microprocessor architecture)

Emergency medicine

• Emergency Severity Index
  Emergency Severity Index
  The Emergency Severity Index is a five-level emergency department triage algorithm that provides clinically relevant stratification of patients into five groups from 1 to 5 on the basis of acuity and resource needs...
  
  , a triage algorithm for the hospital emergency department

Others

• esi is the ISO 639-3 code for the North Alaskan Inupiat language
  Inupiat language
  The Inupiat language, also known as Inupiatun, Inupiaq, Iñupiaq, Inyupiaq, Inyupiat, Inyupeat, Inyupik, and Inupik, is a group of dialects of the Inuit language, spoken in northern and northwestern Alaska. The Iñupiaq language is a member of the Eskimo languages group. There are roughly 2,100...
  
  
• Electromagnetic source imaging
  Electromagnetic source imaging
  Electromagnetic Source Imaging is a functional imaging technique, which uses Electroencephalography and/or Magnetoencephalography measurements to map functional areas of the Cerebral cortex.See Magnetoencephalography for more information....
  
  
• Environmental Sustainability Index
  Environmental Sustainability Index
  The Environmental Sustainability Index ' was a composite index published from 1999 to 2005 that tracked 21 elements of environmental sustainability covering natural resource endowments, past and present pollution levels, environmental management efforts, contributions to protection of the global...
  
  
• Epidural Steroid Injection
• Escadron spécial d'intervention, Belgium's former counter-terrorism force, now the Federal Police Special Units
• Espinosa, Minas Gerais, Brazil airport IATA code
• Ethical Sensory Introvert, in socionics
• Export substitution industrialization (ESI), sometimes called Export-Oriented Industrialisation (EOI), an economic trade policy

• Esi Tonga
  Esi Tonga
  Esikeli Tonga is an Australian professional rugby league footballer for the Gold Coast Titans in the National Rugby League...
  
  (1988-), a rugby league player