RD
- 6 Repair Depot
- Dietitian
- Domain of a function
- Dominican peso
- Emblem for Reserve Force Service
- List of Latin-script digraphs
- Ordinal indicator
- Priesthood in the Catholic Church
- RD (group)
- RD-8
- Rainbow Dash
- Rata Die
- Rate–distortion optimization
- Reader's Digest
- Reading disability
- Real Drive
- Recurring deposit
- Red Line (Washington Metro)
- Regional district
- Remote desktop (disambiguation)
- Research and development
- Reserve Decoration
- Resident director
- Restrictive dermopathy
- Retinal detachment
- Richmond and Danville Railroad
- Rider (software)
- Rilindja Demokratike
- Route distinguisher
- Ruby Document format
- Rural dean
- Rural delivery service
- Rutherford (unit)
- Ryan International Airlines
- SpaceHey
- USDA Rural Development