Look up fir in Wiktionary, the free dictionary.

FIR refer to:

• Finite impulse response, a digital filter type
• Forschungsinstitut für Rationalisierung, the Research Institute for Operations Management in English
• French Indian rupee, defunct currency in French India
• far infrared, i.e. infrared radiation of long wave length
• In India, First Information Report, the first report of crime filed by police
• Flight Information Region, a type of airspace
• F.I.R., a Mandarin pop music group from Taiwan
• in web design, Fahrner Image Replacement, a method for replacing text with an image using style sheets
• Federazione Italiana Rugby, the rugby union governing body in Italy
• Infrared Data Association, Fast Infrared
• Free ideal ring in mathematics

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