- D4 stands for Dillinger Four (band)
- D4 stands for Delta4 (work process and performance improvement system for sales organizations)
- d4 stands for 4-Sided Die (gaming)
- D4 stands for Fourth Generation Channel Bank (48 Voice Channels on 2 T-1s or 1 T-1c)
- D4 stands for Degrade, Disrupt, Deny, Destroy
- D4 stands for Decontamination, Dismantlement, Deactivation, and Decommissioning (US DoE)
- D4 stands for MI-5 Special Services
Abbreviations And Their Meaning