| Acronym | Definition |
|---|
| FIR | Finite Impulse Response |
| FIR | Far Infrared |
| FIR | Federal Inland Revenue (Nigeria) |
| FIR | Fixed Income Research |
| FIR | Fortune International Realty (Florida) |
| FIR | Falling in Reverse (band) |
| FIR | First Information Report |
| FIR | Federal Inspection Report (US FEMA) |
| FIR | Fast Infrared |
| FIR | For Immediate Release |
| FIR | Federazione Italiana Rugby (Italian: Italian Rugby Federation) |
| FIR | Fiscal Impact Report (various locations) |
| FIR | Flight Information Region (aircraft) |
| FIR | Films in Review (publication) |
| FIR | Field Inspection Report (various locations) |
| FIR | Fairyland in Reality (band; Taiwan) |
| FIR | Fonds d'Intervention Régional (French: Regional Intervention Fund) |
| FIR | Forum pour l'Investissement Responsable (French: Forum for Responsible Investment) |
| FIR | Financial Information Reporting |
| FIR | Fast Infra Red |
| FIR | Far Infra Red |
| FIR | Fédération Internationale du Recyclage (French: International Federation of Recycling; Netherlands) |
| FIR | Forschungsinstitut für Rationalisierung (German Institute for Operations Management) |
| FIR | Fahrner Image Replacement (CSS method for replacing text with an image) |
| FIR | Firefly Books |
| FIR | France Initiative Réseau (French: France Initiative Network) |
| FIR | Flood Insurance Report (US FEMA) |
| FIR | Fédération Internationale de Relaxologie (French: International Federation of Relaxology) |
| FIR | Fonds Institutionnel de la Recherche (French: Institutional Research Fund; Canada) |
| FIR | Fish Inspection Regulations (Canada) |
| FIR | Field Inspection Review |
| FIR | Fully Indexed Rate |
| FIR | First Investigation Report |
| FIR | Fournitures Industrielles du Rhône (French: Rhone Industrial Supplies; Rhone, France) |
| FIR | Final Inspection Report |
| FIR | Field Investigation Report |
| FIR | Fairways in Regulation (golf) |
| FIR | Finite-duration Impulse Response |
| FIR | Field Contact Report |
| FIR | Fluids Integrated Rack |
| FIR | First Impression Report |
| FIR | Full Indicator Reading |
| FIR | Field Intelligence Report |
| FIR | Flying Insects and Robots |
| FIR | Flight Incident Recorder |
| FIR | Found Iron Rod |
| FIR | Facility Inspection Report |
| FIR | Full Inspection Report |
| FIR | Financial Inventory Report |
| FIR | Federal Industry and Research (type of grant) |
| FIR | Fault Isolation Resolution |
| FIR | Failure Insensitive Routing |
| FIR | Flight Information Report |
| FIR | Flow Induced Resonance (underwater acoustics) |
| FIR | Final Inspection Record |
| FIR | Far Infrasound |
| FIR | Frequency Induced Resonance |
| FIR | Future Issue Requirement |
| FIR | Functional Item Repair/Replacement |
| FIR | Field Incident Rate |