EI

EI or Ei may stand for:
* "Earth Interactions", a journal
* ei, a digraph found in some writing systems
* Ei, an abbreviation for the IEEE prefix exbi which represents 2⁶⁰.
* Ei, a town located in Kagoshima, Japan.
* "E.I. (song)", a song by the rapper Nelly
* "E/I": Educational and informational programming that is required for network television broadcast channels in the United States
* ei, a form of the Finnish negative verb
* EI, acronym for Engineer Intern, a probationary period lasting up to 5 years before an engineering graduate can become a Professional Engineer
* Education International, a global union federation
* Electron ionisation an ionisation method in Mass spectrometry
* Electronic ignition
* Electronic Intifada, a non-profit organization providing news and editorials on the Israeli-Palestinian conflict.
* Emerald Isle, North Carolina, a beach in the U.S. state of North Carolina
* Emotional intelligence
* Employment insurance, a Canadian government benefit
* Encyclopaedia of Islam, scholarly encyclopaedia covering many aspects of Islam
* Energy Institute
* Enterprise integration
* Enterprise Ireland an Irish economic development agency
* Environmental illness, an increased sensitivity to common chemicals also called multiple chemical sensitivity.
* Equine influenza, also known as Horse Flu
* Extreme ironing, an extreme sport
* E_I or ionization energy, the energy required to remove one electron from one atom to another.
* The exponential integral, mathematical function $\{\; m\; Ei\}(x)=-int\_\{-x\}^\{infty\}\; frac\{e^\{-t\{t\}\; \{\; m\; d\}t$
* The product of the Young's modulus E and the second moment of inertia I.
* The Republic of Ireland, in a number of meanings, including ITU prefixes, from the Irish language name Éire.
* The Aer Lingus airlines IATA airline designator