EI or Ei may refer to:

Arts and mediaEdit

Businesses and organizationsEdit



Science, technology, and mathematicsEdit

  • Ei (prefix symbol), the prefix abbreviation of the binary unit prefix "exbi"
  • Earth Interactions, a scientific journal published by the American Meteorological Society, American Geophysical Union, and Association of American Geographers
  • Ei Compendex, an engineering bibliographic database
  • Electron ionization, an ionization method in which energetic electrons interact with gas phase atoms or molecules to produce ions
  • Electronic ignition, a variety of modern ignition system
  • Engineering Index, an article index for engineering journals
  • Engineer intern, an intermediary step to becoming a Professional Engineer
  • Environmental illness (multiple chemical sensitivity), a chronic medical condition characterized by symptoms that the affected person attributes to exposure to low levels of chemicals
  • Ionization energy (EI), the energy required to remove one electron from one atom to another
  • Equine influenza, the disease caused by strains of Influenza A that are enzootic in horse species
  • Exponential integral, a special function defined on the complex plane given the symbol Ei

Other usesEdit