Material Systems Directorate 
Material Support Date 
Mini Secure Digital 
Microgravity Science Division 
most significant digit 
Microsoft System Diagnostics 
Maintenance Support Device 
Materials Sciences Division 
Management Systems Division 
MARS Supplemental Data 
Mass Selective Detector 
MASUDA 
mean square displacement 
minimum safe distance 
Ministry of Social Development 
Macromolecular Structure Database 
Manual Simulations Division 
Marble spleen disease 
marginal support date 
Marine Safety Detachment 
Mass Storage Device 
Master of Science in Dentistry 
Master Scuba Diver 
Master Slave Determination 
Materials Science Division 
Matrix Spike Duplication 
Mean Solar Distance 
Medium Speed Data 
Metropolitan Sewer District 
Microsoft Diagnostics