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
• 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
• 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.