| Acronym | Definition |
|---|
| UDN➣União Democrática Nacional (Portuguese: National Democratic Union; Brazilian political group) |
| UDN➣Ubiquity Developer Network |
| UDN➣University Developers Network |
| UDN➣Universal Domain Network |
| UDN➣Unreal Developer Network |
| UDN➣United Daily News (newspaper; China) |
| UDN➣Uganda Debt Network |
| UDN➣Unreal Developer Network (Epic Games) |
| UDN➣Ubiquity Developer Network (software company community) |
| UDN➣Unique Device Name |
| UDN➣Unión Democrática Nacionalista |
| UDN➣Unintelligent Design Network, Inc. |