| R & D | Research and Development |
| R&D | Research and Development |
| RADAR | Radio Detecting and Ranging |
| RAM | Random Access Memory |
| RAW | Research & Analysis Wing |
| RBI | Reserve Bank of India |
| RCC | Reinforced Cement Concrete |
| RDX | Research Department Explosive (Cyclotrim-ethylin Trinitrate) |
| RIMC | Rashtriya Indian Military College |
| RISC | Reduced instruction-set computing |
| RLEGP | Rural Landless Employment Guarantee Programme |
| RMS | Railway Mail Service |
| RNA | Ribonucleic acid |
| ROM | Read Only Memory |
| RPM | Revolutions Per Minute |
| RSS | Rashtriya Swayamsevak Sangh |
| RTI | Right to Information |
| RTO | Regional Transport Officer |