Irish vehicle registration for Dublin
• radio interference
• radioisotope
• Railway Inspectorate
• refractive index
• Regimental Institute
• Regina et Imperatrix (Latin: Queen and Empress)
• Shipping (Italy ) Registro Italiano Navale (classification society)
• (or R/I) reinsurance
• religious instruction
• report of investigation
• international vehicle registration for Republic of Indonesia
• Rex et Imperator (Latin: King and Emperor)
• Rhode Island (abbrev. or postcode)
• Rockwell International Corporation
• Rotary International
• (Member of the) Royal Institute of Painters in Water Colours
• Royal Institution