Depends on the context:
EDM
Electronic Document Management
Electronic Document Management
Enterprise Data Management
Engineering Data Management
Entity Data Model
Enterprise Desktop Management
Extended Data Message
Enhanced Data Mode
Express Development Methodology
External Digital Modulation
SEM
Strategic Enterprise Management
Software Engineering and Middleware
Security Event Manager
SQL Enterprise Manager
Systems Engineering Management
Systems Engineering Manager
System Engineering Methodology
Simulation, Engineering, and Modeling
Secure Ethernet Multiplexer