RID
- Isaiah ben Mali di Trani (the Elder)
- RID (insect repellent)
- Radial immunodiffusion
- Radionuclide identification device
- Reactor Institute Delft
- Real-time Inter-network Defense
- Refractive index detector
- Registry of Interpreters for the Deaf
- Relative identifier
- Rivista Italiana Difesa
- Robots in Disguise
- Rock Island District
- Royal Institute Dictionary