| Acronym | Meaning |
| RDD | Radiological Dispersion Device |
| HRV | Croatian Language (ISO 639-2 Code) |
| HAZ | Heat-Affected Zone |
| SCUFN | Sub-Committee On Undersea Feature Names (of GEBCO) |
| SLV | El Salvador (ISO 3166 Trigram) |
| MLG | Malagasy Language (ISO 639-2 Code) |
| SOL | S**t Out Of Luck |
| YK | Yottakelvin |
| TR | Turkey (ISO 3166 Digram) |
| UPU | Universal Postal Union |