| Acronym | Definition |
|---|
| MTA | Mail Transport Agent (e-mail) |
| MTA | Metropolitan Transportation Authority (New York, NY, USA) |
| MTA | Mail Transfer Agent (Internet E-Mail) |
| MTA | Mount Allison University |
| MTA | Los Angeles County Metropolitan Transportation Authority |
| MTA | Magyar Tudományos Akadémia (Hungarian Academy of Sciences, Budapest) |
| MTA | Multimodal Treatment Study of Children with ADHD (Attention Deficit Hyperactivity Disorder; US NIMH) |
| MTA | Motor Trade Association |
| MTA | Multi Theft Auto (game) |
| MTA | Multimedia Terminal Adapter |
| MTA | Mage: the Awakening (gaming) |
| MTA | Mineral Trioxide Aggregate |
| MTA | Monthly Treasury Average |
| MTA | Monthly Treasury Average (ARM index) |
| MTA | Maine Turnpike Authority |
| MTA | Microsoft Technology Associate (certification) |
| MTA | Maccabi Tel Aviv (Israeli basketball team) |
| MTA | Muslim Television Ahmadiyya (UK) |
| MTA | Marin Telecommunications Agency (Novato, CA) |
| MTA | Maintenance Task Analysis |
| MTA | Medizinisch-Technische Assistentin (German Profession in Medical Sector) |
| MTA | Mendocino Transit Authority (California) |
| MTA | Mage: the Ascension (game) |
| MTA | Multi-Threaded Architecture |
| MTA | Manchester Transit Authority (New Hampshire, USA) |
| MTA | Montana Telecommunications Association (formerly Montana Telephone Association) |
| MTA | M Technology Association (user group for the M [MUMPS] programming language) |
| MTA | Multiple Terminal Access |
| MTA | Motorcycle Touring Association (US) |
| MTA | Muslim TV Ahmadiyya (satellite channel) |
| MTA | Multiple Technology Appraisal (National Health Service; UK) |
| MTA | Mpumalanga Tourism Authority (South Africa) |
| MTA | Mobile Task Automation |
| MTA | Model Turned Actress |
| MTA | Minnesota Telecommunications Association |
| MTA | Microwave Transition Analyzer |
| MTA | Montana Telephone Association (now Montana Telecommunications Association) |
| MTA | Minnesota Trappers Association |
| MTA | Minnesota Transit Authority |
| MTA | Mass Termination Assembly (computer engineering) |
| MTA | Macintosh Telephony Architecture (Apple) |
| MTA | Motorcycle Tires and Accessories |
| MTA | Military Transportation Authorization |
| MTA | Maryland Transit Association |
| MTA | Minnesota Trout Association |
| MTA | Muhlenberg Theatre Association (Muhlenberg College) |
| MTA | Media Termination Adapters |
| MTA | Metropolitan Transit Area |
| MTA | Multi-TADIL Architecture |
| MTA | Maintenance Technical Assistance |
| MTA | Multiple Time Around (radar systems) |
| MTA | Medical Tourism Association, Inc. |
| MTA | Music Teachers' Association of New South Wales |
| MTA | Maitland Trail Association (Goderich, ON, Canada) |
| MTA | Modular Test Architecture |
| MTA | Message Transport Address (Sprint) |
| MTA | Manual Target Acquisition |
| MTA | Midwest Telecommunications Association |
| MTA | Materiel Transfer Agreement |
| MTA | Manhattan Torah Academy |
| MTA | Militärisch-Technisches Abkommen (German: Treaty on Military Technologies) |
| MTA | Multimedia Terminal and Applications |
| MTA | Marine Tactical Automated Command and Control System |
| MTA | Magnetic Torque Assembly |
| MTA | Maghrébine de Transport & Auxiliaires |
| MTA | MAC Transportation Request |
| MTA | Manufacturing Technology Activity |
| MTA | Multi-Object Trace Assertion |
| MTA | Mission Tasking Agreement |
| MTA | Mutual Training Association |
| MTA | Materials Testing Activity |
| MTA | Matched Typed Address (philately) |
| MTA | Maximum Turning Angle |
| MTA | Main Training Area |
| MTA | Mine Threat Area |
| MTA | Mac Technology Association (UK Trade Association for Apple Mac resellers) |
| MTA | Maryland Transit Authority |
| MTA | Maryland Taxpayers Association |
| MTA | Mathematics Teachers Association |
| MTA | Media Terminal Adaptor (cable telephony) |
| MTA | Military Testing Association |
| MTA | Minnesota Taxpayers Association |
| MTA | Market Technicians Association (financial markets) |
| MTA | Metropolitan Transit Authority (Boston, now MBTA) |
| MTA | Mother Tongue Annoyances (linguistics; blog) |
| MTA | Maryland Transit Administration |
| MTA | Material Transfer Agreement |
| MTA | Malta Tourism Authority |
| MTA | Managing the Atom |
| MTA | Mid-Term Appraisal |
| MTA | Medical Technical Assistant |
| MTA | Minnesota Telephone Association |
| MTA | Massachusetts Teachers Association |
| MTA | Military Training Area |
| MTA | Military Transport Aircraft |
| MTA | Mass Transit Administration |
| MTA | Massachusetts Turnpike Authority |
| MTA | Major Trading Area(s) |
| MTA | Major Training Area |
| MTA | Metallic Test Access (Nortel) |
| MTA | Michigan Townships Association |
| MTA | Memo To Agent |
| MTA | Message Traffic Analysis |
| MTA | Message Transfer Agent |
| MTA | Master of Tourism Administration |
| MTA | Maximum Time Aloft |
| MTA | Metropolitan Trading Area |
| MTA | Management and Technical Assistance |
| MTA | military training agreement (US DoD) |
| MTA | Meet the Author |
| MTA | Medical Technology Assessment |
| MTA | Major Technical Area |
| MTA | Mercato Telematico Azionario (Italian: Online Stock Market) |
| MTA | Mid-Term Adjustment (insurance policy change) |
| MTA | Million Metric Tons Annually |