| Acronym | Definition |
|---|
| RI | Rhode Island (US postal abbreviation) |
| RI | Rock Island (various locations) |
| RI | Rotary International |
| RI | Republic of Indonesia |
| RI | Robotics Institute |
| RI | Remedial Investigation |
| RI | River Island (clothing; UK) |
| RI | Reference Implementation |
| RI | Relevant Information |
| RI | Relief International |
| RI | Reissue |
| RI | Refugees International |
| RI | Respiratory Infection (illness) |
| RI | Relations Internationales (French: International Relations) |
| RI | Reinsurance |
| RI | Red Ink (band) |
| RI | Repubblica Italiana (Italian Republic) |
| RI | Refractive Index |
| RI | Roosevelt Island (New York, NY) |
| RI | Raffles Institution (Singapore) |
| RI | Reproductive Isolation (biology) |
| RI | Request for Information (usually seen as RFI) |
| RI | Responsible Investment |
| RI | Régiment d'Infanterie (French: Infantry Regiment) |
| RI | Ring It |
| RI | Residual Income |
| RI | Risques Industriels (French: Industrial Risks) |
| RI | Relações Internacionais (Brazil; International Relations) |
| RI | Religious Instruction |
| RI | Reliability Index |
| RI | Renal Insufficiency (kidney disorder) |
| RI | Ring Indicator (for Modem) |
| RI | Rijeka, Croatia (license plate) |
| RI | Rotate In (Hyper Logo Turtle graphics command) |
| RI | Reliability Improvement |
| RI | Referential Integrity (database rules) |
| RI | Royal Infirmary (UK) |
| RI | Righteous Indignation |
| RI | Rigorous Imprisonment (police) |
| RI | Research Infrastructure |
| RI | Rank Indicator |
| RI | Review Item |
| RI | Rockwell International |
| RI | Radio Interference |
| RI | Resistance Index |
| RI | Recombinant Inbred |
| RI | Rockefeller Institute |
| RI | Rehabilitation International (New York, NY) |
| RI | Retention Index |
| RI | Rieti, Lazio (Italian province) |
| RI | Report of Investigation (NIOSH) |
| RI | Radiation Intensity |
| RI | Runway Incursion |
| RI | Re-Interview (census) |
| RI | Rutherford Institute |
| RI | Research Instrument |
| RI | Roslin Institute (UK) |
| RI | Relative Inaccuracy (measurement) |
| RI | Risk-Informed (Nuclear Power) |
| RI | Registered Importer (US National Highway Traffic Safety Administration) |
| RI | Receiving Inspection |
| RI | Royal Institute of Painters in Water Colours (UK) |
| RI | Registration Intake |
| RI | Routing Indicator (US DoD) |
| RI | Rise Inside (band) |
| RI | Record Item |
| RI | Rex Imperator (Latin: King Emperor; British imperial title) |
| RI | Rinnovamento Italiano (Italian Renewal Party) |
| RI | Recruit Instruction (US Navy) |
| RI | Research Interviewer |
| RI | Readership Institute (Northwestern University) |
| RI | Regional Ileitis (pig disease) |
| RI | Random Individual |
| RI | Routing Identifier |
| RI | Rosenbluth International |
| RI | Resistance-Inductance |
| RI | Random Insanity (online comic strip) |
| RI | Random Insanity (gaming community) |
| RI | Routes International |
| RI | Reinforced Insulation |
| RI | Ranger Instructor (US Army Ranger School) |
| RI | Reverse Integration (computer source code merge promotion process) |
| RI | Residual Image |
| RI | Reconnaissance Investigation |
| RI | Retreats International |
| RI | Resonance Integral |
| RI | Right Inboard |
| RI | Reconnaissance Inspection |
| RI | Republiek Indonesie (Dutch) |
| RI | Ramblin' Irishman |
| RI | Randomly Interleaved |
| RI | Règlement Immédiat (cash settlement of French shares) |
| RI | Refractory Index |
| RI | Repulsion Induction |
| RI | Member of the Real Estate Institute of British Columbia |
| RI | Reporting Identifier |
| RI | Reactor Incident |
| RI | Rhythmic Initiation (PNF technique) |
| RI | Restricted Issue |
| RI | Repair and Iterate (part of Generate-and-Repair Machine Translation) |
| RI | Remedial Inspection |
| RI | US Revenue Potato Tax (Scott Catalogue prefix; philately) |
| RI | Reportable Increment |