| Abbreviation | Definition |
|---|---|
| MCT | Minimum Connection Time |
| MCTA | Multi-Carrier Traffic Allocation |
| MCU | Multi-cast Conferencing Unit |
| MD5 | Message Digest 5 |
| MDA | Mail Delivery Agent |
| MDA | Message Delivery Area |
| MDA | Multiple Device Access |
| MDAP | Mediated Digest Authentication Protocol |
| MDB | Multi-Drop Bus |
| MDC | Maintenance Domain Controller |
| MDCX | Modified Connection |
| MDI | Media Dependent Interface |
| MDI | Medium Dependant Interface |
| MDN | Message Disposition Notification |
| MDN | Mozilla Developer Network |
| MDNS | Multicast Domain Name System |
| MDO6 | Multicast Destination Option on IPv6 |
| MDP | Markov Decision Processes |
| MDQS | Multi-Device Queueing System |
| MDR | Multiservices Dynamic Reservation |