| Acronym | Definition |
|---|
| MAI | Mail (File Name Extension) |
| MAI | Multilateral Agreement on Investment |
| MAI | Ministerul Afacerilor Interne (Romanian: Ministry of the Interior; Moldova) |
| MAI | Multiple Access Interference |
| MAI | Modelo de Atención Integral (Spanish: Integral Attention Model; healthcare) |
| MAI | Ministerul Administratiei si Internelor (Romanian: Ministry of the Interior) |
| MAI | Maius (Latin: May) |
| MAI | Martial Arts Instructor (various organizations) |
| MAI | Montréal, Arts Interculturels (French: Montreal, Intercultural Arts; Canada) |
| MAI | Mécanique et Automatismes Industriels (French: Mechanical and Industrial Automation) |
| MAI | Mobile App Install (advertising) |
| MAI | Ministério da Administração Interna (Portugal) |
| MAI | Management Association of Illinois |
| MAI | Mycobacterium Avium-Intracellulare |
| MAI | Member, Appraisal Institute (real estate) |
| MAI | Minority AIDS Initiative |
| MAI | Moscow Aviation Institute |
| MAI | Mean Annual Increment (forestry) |
| MAI | Market for Alternative Investment (Second Board on Thailand's Exchange) |
| MAI | Machine-Aided Indexing (computing) |
| MAI | Monash Asia Institute |
| MAI | Mcdonald Associates, Inc. (Illinois) |
| MAI | McAfee Associates, Inc. (software; various locations) |
| MAI | Meinl Airports International (Austria) |
| MAI | Marine Asset Intelligence (Caterpillar, Inc.) |
| MAI | Manufacturers' Association of Israel |
| MAI | Merchant Administration Interface (various businesses) |
| MAI | Media Action International |
| MAI | Made As Instructed |
| MAI | Middleware-Application Interaction |
| MAI | Medical Action Industries Inc. (Brentwood, NY) |
| MAI | Marriage Alive International (est. 1983) |
| MAI | Median Area Income |
| MAI | Market Access Intelligence (World Trade Organization) |
| MAI | Multilevel Assessment Instrument |
| MAI | Major Automated Information |
| MAI | Migration and Asylum Initiative (now part of MARRI) |
| MAI | Military Assistance Institute |
| MAI | Measurement, Analysis and Improvement |
| MAI | Myanmar Airway International |
| MAI | Medication Assisted Intubation |
| MAI | Management Assistance Incorporated |
| MAI | Material Annex Item |
| MAI | General Appraisal Member of the Appraisal Institute (formerly Member Appraisal Institute) |
| MAI | Multiple Action Interaction |
| MAI | Mesna, Adriamycin, and Ifosfamide (chemotherapy regimen) |
| MAI | Medical Awareness Institute (San Diego, CA) |
| MAI | Master Assessment Index |
| MAI | Malaysian Association of Illinois (Southern Illinois University; Carbondale, IL) |