IR

Ir or ir may refer to:

• the abbreviation (Ir.) for the title of Ingénieur (Engineer), a person practicing the profession of engineering
• Iridium (chemical symbol Ir), the 77th element
• .ir, the Internet country code top-level domain for Iran

IR may refer to:

• Iran, which has the country code IR
• International Relations, in political science, the study of foreign affairs of and relations among states
• Investor relations, a management responsibility in which companies disclose information for regulatory compliance and for bond/share-holders to make investment judgments

Organizations

• Illinois Railway
• Indian Railways, the state-owned railway company of India
• Industrial relations (labor relations)
• Ingersoll Rand (NYSE trading symbol IR)
• Integrated Resort, a euphemism for a casino in Singapore
• Internal Revenue Service, the United States government agency that collects taxes and enforces the internal revenue laws
• International Rectifier, a manufacturer of power semiconductors
• International Rescue Corps, an organization inspired by the Thunderbirds TV series
• Iran Air (IATA airline code IR)
• Iarnród Éireann (Irish Rail), the national passenger and freight railway system of the Republic of Ireland
• Islamic Relief

Science and medicine

• Incident report
• Infrared, a portion of the electromagnetic radiation spectrum
• Insulin receptor, a transmembrane receptor that is activated by insulin
• Insulin resistance
• Inverted repeat, a sequence of nucleotides that is the reversed complement of another sequence further downstream
• Interventional radiology
• Ionizing radiation
• Immediate release (as opposed to sustained release) tablets

Finance

• Interest rate or (when referring to an asset class) interest rate derivative
• Information ratio when referring to risk-adjusted returns of a financial security

Computing

• Adobe ImageReady, a bitmap graphics editor shipped with Adobe Photoshop by Adobe Systems
• 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

Popular culture

• I.R. Baboon from the cartoon series I Am Weasel
• In Rainbows, the seventh studio album by the alternative rock band Radiohead

Other

• Injured reserve list, a reserve list for professional teams to use if a player is injured and unable to play for an extended time
• International rules football a hybrid code of football
• Independent-Republican Party of Minnesota, currently known as Republican Party of Minnesota
• International relations, in political science, the study of foreign affairs of and relations among states
• Instrument rating, the qualifications a pilot must have in order to fly under Instrument Flight Rules (IFR)
• Impulse response, is a function of a dynamic system of its output when presented with a brief input signal
• Imaginary Realities, a MUD community online magazine
• International Rescue (disambiguation)
• Interracial (disambiguation)
• In mathematics, the set of real numbers is sometimes written on computers as "IR", the I standing as the R's double-bar.