ER

ER or Er may refer to:

• Еmergency room, a department of a medical facility that specializes in the acute care of patients without any prior appointments
• ER, the ISO 3166-1 alpha-2 code of the country of Eritrea
• ER, the IATA code of Astar Air Cargo

In media:

• ER (TV series), a 1994–2009 American medical drama television series
• E/R, a 1984–1985 American television sitcom
• Eesti Rahvusringhääling, an Estonian public broadcasting organization
• Er, an album by Nils Petter Molvær
• Chico Enterprise-Record, the daily newspaper of Chico, California

In natural science:

• Erbium, a chemical element
• Relative static permittivity, a concept in chemistry represented as $\epsilon _{r}$
• Estrogen receptor, a type of protein molecule
• Endoplasmic reticulum, a type of organelle in cell biology
• Equine Exertional Rhabdomyolysis, a syndrome that damages the muscle tissue in horses

Parts of language:

• Er (Cyrillic), the eighteenth letter of the Cyrillic alphabet
• The suffix -er, which is added to an adjective or adverb to describe a degree of comparison
• "er", a filler word

In technology:

• ER (Extended Range), a classification of missiles and aircraft that indicates an extended travel capability
• Engineer, a profession that applies knowledge to develop solutions to meet economic and societal needs
• Entity-relationship model, an abstract and conceptual representation of data
• Error Resilience, an audio coding method used in MPEG-4 Part 3

Other uses

• Er (Biblical name), in the Biblical Book of Genesis, the eldest son of Judah
• Er., an abbreviation used in Hebrew for Moed
• Er, the subject of Plato's Myth of Er
• Earned run, a term in the game of baseball that denotes any run for which the pitcher is held accountable
• Evidential reasoning approach, a concept in Decision Theory
• Elizabeth Regina, an alternate name of Queen Elizabeth
• Eduardus Rex. an alternate name for King Edward