| Acronym | Definition |
|---|
| ARI | Ayn Rand Institute |
| ARI | Air-Conditioning and Refrigeration Institute |
| ARI | Acute Respiratory Infection |
| ARI | Autism Research Institute |
| ARI | Agricultural Research Institute |
| ARI | Army Research Institute |
| ARI | Automotive Resources International |
| ARI | Asia Research Institute |
| ARI | Arthritis and Rheumatism International |
| ARI | Autoridad de la Región Interoceánica (Inter-Oceanic Authority) |
| ARI | Advanced Research Institute |
| ARI | Action Research International (online journal) |
| ARI | Average Recurrence Interval |
| ARI | Afirmación para una República Igualitaria (Spanish; Argentina) |
| ARI | Aberdeen Royal Infirmary |
| ARI | Absolute Risk Increase |
| ARI | Aldose Reductase Inhibitor |
| ARI | Andean Regional Initiative |
| ARI | Allotments Regeneration Initiative (UK) |
| ARI | Archaeological Research Institute |
| ARI | Autofahrer-Rundfunk-Information |
| ARI | Annual Risk of Infection |
| ARI | All Risk Insurance |
| ARI | Alexandria Research Institute (Alexandria, Virginia; Virginia Tech) |
| ARI | Accelerated Research Initiative |
| ARI | Airpower Research Institute |
| ARI | Acute Renal Insufficiency |
| ARI | Alcohol Related Incident |
| ARI | Arica, Chile - Chacalluta (Airport Code) |
| ARI | annual recurrence interval (hydrology) |
| ARI | Aileron Rudder Interconnect |
| ARI | Acoustics Research Institute |
| ARI | ANSTO Radiopharmaceuticals and Industrials (Australia) |
| ARI | Aviation Restructure Initiative |
| ARI | Alternate Rod Insertion |
| ARI | Audience Research Institute |
| ARI | Associazione Rebussistica Italiana (Italian Rebus Association) |
| ARI | Applied Research Inc. |
| ARI | Accounting Rate of Interest |
| ARI | Automatic Room Identification |
| ARI | Agrarian Reform Institute |
| ARI | Automatic Return Item |
| ARI | Address Recognized Indicator Bit |
| ARI | Aquifer Risk Index |
| ARI | Agatston Research Institute (Miami Beach, FL, USA) |
| ARI | Asia Rural Institute (Japan) |
| ARI | Aileron to Rudder Interconnect |
| ARI | Automatic Rudder Interconnect |
| ARI | Associazione Radiamatori Italiani (Italian Ham Radio Association) |
| ARI | Activity Routing Identifier |
| ARI | Attitude Reference Indicator |
| ARI | Affordable Readiness Initiative |
| ARI | ATS R&D IPT |
| ARI | Abbey Road Interactive Studios (London, England) |
| ARI | Addressee Routing Indicator |
| ARI | Actuarial Removal Interval |
| ARI | Armrest Rotary Input |
| ARI | Advanced Rigid Insulation |
| ARI | Automatic Railway Information |