Here are a few. There are more. I always try to mean the one that is most appropriate in the moment:
MA Massachusetts (US postal abbreviation)
MA Mature Audiences (TV program rating)
MA Milliampere
MA Mildly Amused
MA Market America (independent entrepenurial corporation founded by James H Ridinger)
MA Master
MA Materials
MA Moving Average
MA Medical Assistance
MA Maintenance
MA Medical Assistant
MA Meta Analysis
MA Military Academy (West Point, NY)
MA Management Accounting
MA Microsoft Access
MA Move Along
MA Mannheim, Germany (license plate)
MA Manual (welding)
MA Mathematics
MA Mid-Atlantic (region; various organizations)
MA Metropolitan Area
MA Monoclonal Antibody
MA Manitoba
MA Morocco (ISO country code, top level domain)
MA Multiple Access
MA Madagascar (Malagasy)
MA Management Agent (metadirectory services)
MA Martial Artist (gaming, Anarchy Online)
MA Medicare Advantage
MA Mexican American (classification)
MA Management Analyst
MA Military Applications
MA Massive Attack (band)
MA Maranhao (Brazil)
MA Map Analysis
MA Million Years (geology)
MA Mission Accomplished
MA Marin Academy (California)
MA Mittelalter (German: Middle Ages)
MA Methamphetamine
MA Maranhão (Brazilian state)
MA Medical Advisor
MA Michael Alexander (jewelry)
MA Military Attaché (US Navy)
MA Mission Assurance (Homeland Defense)
MA Marijuana Anonymous
MA Maintenance Agreement
MA Multiple Award
MA Martha Argerich (pianist)
MA Mechanical Advantage (machines)
MA Management Activity
MA Measurement and Analysis (process area; Capability Maturity Model Integration)
MA Maanantai (Finnish: Monday)
MA Morbid Angel (band)
MA Master-at-Arms (military rating)
MA Martial Artist (gaming)
MA Maritime Administration
MA Member Association (various organizations)
MA Memetic Algorithm (evolutionary computing)
MA Maleic Anhydride
MA Management Accounts
MA Modified Atmosphere
MA Mental Age
MA Marketing Authorization
MA Mean Average (mathematics)
MA Metropolitan Area Network
MA Multi-Access
MA Magister Artium (Master of Arts)
MA Missed Abortion
MA Multimedia Authoring
MA Mission Area
MA Mandelic Acid
MA Modern Apprenticeship
MA Mobile Armor (Gundam series)
MA Mobile Assistant
MA Monitoring Agency
MA Major Arcana (Lineage 2 game armor set)
MA Medical Attendant
MA Mechanical Animals (Marilyn Manson album)
MA Mission Analysis
MA Microaneurysm (ophthalmology)
MA Metabolic Analyzer (US NASA)
MA Mass Analyzer
MA Molecular Absorption
MA Materials Analyst
MA Missed Approach
MA Military Assistant
MA Moored Alongside
MA Maintenance Action
MA Mortuary Affairs
MA Maître Auxiliaire (French: Adjunct Professor)
MA Missed Appointment
MA Medical Administrator
MA Minnehaha Academy (Minneapolis)
MA Motorcycling Australia
MA Mission Assignment
MA Masurium (element)
MA Mobility Agent
MA Multiple Answer
MA Managed Availability (computing)
MA Minor Arterial (State highway Information)
MA Minor Actinide
MA Maximum Allowance
MA Margin Agreement
MA Message Analysis
MA Methanandamide
MA Main Assist (Everquest)
MA Middle Assyrian
MA Marshalling Area
MA Makarska, Croatia (license plate)
MA Magnetic Amplifier
MA Mission Abort
MA Maintenance Administrator
MA Master Administrator
MA Manual Assist (nursing)
MA Military Aircrew
MA Maintaining Activity
MA Management Advocate
MA Music Ant (online guide for music software)
MA Maître Ès Arts (French: Master of Arts)
MA Mega Annum (one million years, geological chronology)
MA Mobilization Assistant
MA Merchandise Analyst (retail)
MA Maintainability Analysis
MA Maintenance and Adaptation (ATMF)
MA Mobile Allocation (PCS - GSM)
MA Manufacturing Approval
MA Mesh Antenna
MA Motorist Assist
MA Machine Accountant (Naval Rating)
MA Memory Administration
MA MatureAsskickers (gaming clan)
MA Mini Alert (System Sensor Sounder)
MA Mechanical Ambush
MA Master of Audiology
MA Multi-Alert (system sensor brand name)
MA MediArchive (website)
MA Magical Alliance (gaming group)
MA MJU Alert (Hekimian)
MA Willys-Overland 1/4 Ton 4 X 4 Truck (1st Model of WWII Jeep)
MA Malev Hungarian Airlines Limited - Hungary (IATA airline code)
MA Makeshift Apathy (Michigan band))
MA MANPRINT Assessment
MA Multichambered Autoinjector
MA (USN Rating) Master-At-Arms
MA Miscible Accounting