MSL
- MBCGame StarCraft League
- MSLGROUP
- Macedonian Sign Language
- Major Series Lacrosse
- Major Soccer League
- Malagasy Sign Language
- Malaysia Super League
- Maritime Sign Language
- Mars Science Laboratory
- Marshall railway station
- Master Subsidy Lock
- Master of Science in Leadership
- Master of Studies in Law
- Materials Science Laboratory
- Mauritian Sign Language
- Maximum segment lifetime
- Mean sea level
- Medical science liaison
- Memphis Sport Live
- Meta Superintelligence Labs
- Metal (API)
- Metal Shading Language
- Midsternal line
- Milwaukee School of Languages
- Mission and Spacecraft Library
- Moisture sensitivity level
- Moldovan Super Liga
- Mongolian Sign Language
- Moroccan Sign Language
- Multilayer soft lithography
- Multiple single-level
- Mzansi Super League
- Northwest Alabama Regional Airport
- RoboCup Middle Size League
- Royal Microscopical Society
- STS-83