ARI
- Aberdeen Royal Infirmary
- Acoustics Research Institute
- Acute respiratory infection
- Aer Rianta International
- American Refrigerant Institute
- Angel Resource Institute
- Ari (disambiguation)
- Arizona
- Arizona Cardinals
- Arizona Coyotes
- Arizona Diamondbacks
- Arthur Rylah Institute for Environmental Research
- Associazione Radioamatori Italiani
- Astronomisches Rechen-Institut
- Astrophysics Research Institute
- Autism Research Institute
- Autofahrer-Rundfunk-Informationssystem
- Automated readability index
- Avicenna Research Institute
- Ayn Rand Institute
- Chacalluta International Airport
- Civic Coalition ARI
- Major League Baseball
- National Football League
- National Hockey League
- Rand index