ESI

• Earth Similarity Index
• Electrospray ionization, a technique used in mass spectrometry
• Environmental Seismic Intensity scale
• Essential Science Indicators, by Clarivate
• Electronic supplementary information, in scientific publications; for example see coordination polymerization

• Edge Side Includes, a markup language
• Electronically stored information (Federal Rules of Civil Procedure)
• Enclosure Services Interface, a computer protocol used in SCSI enclosures
• Enterprise Southbridge Interface, a motherboard interface
• ESI register, in the x86 microprocessor architecture

• Electromagnetic source imaging
• Emergency Severity Index, a triage algorithm
• Epidural steroid injection

• Electro Scientific Industries, an American high-technology company
• Employees' State Insurance, in India
• ESI Hospital metro station, Delhi
• ESI Hospital metro station (Hyderabad)
• Ernst Strüngmann Institute, a German research institute
• Erwin Schrödinger International Institute for Mathematical Physics, in Austria
• Escadron spécial d'intervention, now the Belgian Federal Police Special Units
• European Stability Initiative, a think tank
• ITT Educational Services, owner of the defunct ITT Technical Institute

• Esi Awuah, Ghanaian academic
• Esi Benyarku (born 1976), Canadian sprinter
• Esi Buobasa, Ghanaian activist
• Esi Edugyan (born 1978), Canadian novelist
• Esi Lufo (born 2001), Albanian footballer
• Esi Sutherland-Addy, Ghanaian academic
• Esikeli Tonga (born 1988), Australian rugby league player

• Enhanced Station Initiative, of the New York City Subway
• Enlightened self-interest, a philosophy in ethics
• Environmental Sustainability Index
• Ethical Sensory Introvert, in socionics
• Export substitution industrialization
• Early supplier involvement, an aspect of supplier integration in new product development
• North Alaskan Inupiatun language (ISO 639-3 code)

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