IR

IR or Ir may refer to:

Arts and media

 * Ir (newspaper), Latvian weekly newspaper
 * Imperator: Rome, a 2019 video game published by Paradox Interactive
 * Integrated resort, a euphemism for a casino in Singapore
 * International Relations (journal), an academic journal
 * I.R. Baboon, a fictional character in the cartoon series I Am Weasel

Transportation

 * Iarnród Éireann (Irish Rail), national passenger and freight railway system of the Republic of Ireland
 * Illinois Railway, US
 * Indian Railways, state-owned railway company of India
 * InterRegio, part of Swiss Federal Railways
 * IR Ishikawa Railway, local railway company in Ishikawa, Japan
 * Iran Air (IATA airline code IR)
 * Israel Railways, state-owned railway company of Israel

Other businesses and organizations

 * Ingersoll Rand (NYSE trading symbol IR)
 * International Rectifier, a former manufacturer of power semiconductors
 * Independent-Republican Party of Minnesota, former name of the Republican Party of Minnesota

Finance

 * Incidence rate (market research)
 * Interest rate, or (when referring to an asset class) interest rate derivative
 * Information ratio, when referring to risk-adjusted returns of a financial security
 * Investor relations, a management responsibility in which companies disclose information for regulatory compliance and for bond/share-holders to make investment judgments

Language

 * Ir (cuneiform), a sign in cuneiform writing
 * Ir language, also known as Ta'Oi language, spoken in parts of Laos and Vietnam
 * Istro-Romanian language

Places

 * Indian Reserve, a section of land in Canada that is controlled by an Indigenous band government
 * Iran, by ISO country code

Biology and medicine

 * Immediate-release, related to time release technology in pharmaceuticals
 * Incidence Rate, in epidemiology
 * Insulin receptor, a transmembrane receptor that is activated by insulin
 * Insulin resistance, a pathological condition
 * Interventional radiology and interventional radiologist, an independent medical specialty
 * Inverted repeat, a sequence of nucleotides that is the reversed complement of another sequence further downstream

Computing

 * .ir, the Internet country code top-level domain for Iran
 * Adobe ImageReady, a bitmap graphics editor shipped with Adobe Photoshop by Adobe Systems
 * Image retention, the LCD and plasma display equivalent of screen burn
 * Information retrieval, the science of searching for information in or as documents or databases
 * Information revolution, one of the theoretical frameworks within which trends in current society can be conceptualized
 * Institutional repository, a digital collection for preserving the intellectual output of an institution
 * Institutional research, the collection, analysis, and reporting of institutional data
 * Instruction register, part of a CPU's control unit
 * Intermediate representation, a computer data structure
 * Internal router

Other uses in science and technology

 * Imaginary numbers, in mathematics, denoted $$\text{i}\mathbb{R}$$ or $iR$
 * Infrared, a portion of the electromagnetic radiation spectrum
 * Impulse response, an output function of a dynamic system presented with a brief input signal
 * Insulation resistance, a measure of insulation material performance
 * Ionizing radiation
 * Iridium, symbol Ir, a chemical element

Other uses

 * Imperial–royal, abbreviation applied to institutions of the Austrian Empire
 * Industrial relations, relations between management and workers in industry
 * Ingenieur, abbreviated ir., an engineer's degree awarded by technical universities in the Netherlands, Belgium, Indonesia, and Malaysia
 * Injured reserve list, a list of professional sports players who are injured and unable to play for an extended time
 * International relations, in political science, the study of foreign affairs of and relations among states
 * International rules football a hybrid code of football