| Abbreviation | Definition |
|---|---|
| RPC | Redd Phoenix Clan |
| RPG | Role Playing Game |
| RPP | Rough Plastic Part |
| RPSS | Rank Probability Skill Score |
| RPSS | Ryukyu Philatelic Specialists Society |
| RQK | Rumpled Quilts Kin |
| RREC | Rolls Royce Enthusiasts Club |
| RSA | Renaissance Society of America |
| RTA | Railroad Tie Association |
| RTN | Reincarnatie Therapie Nederland/ Reincarnation Therapy Netherlands |
| RTPS | Richmond and Twickenham Photographic Society |
| RV | Really Valuable |
| RWYB | Run What You Brung |
| S | Silver |
| SA2 | Sonic Adventure 2 |
| SAE | Scale Auto Enthusiast |
| SAE | Stamped Addressed Envelope |
| SAMA | Society of Anime Manga Addicts |
| SAMCA | South African Model Car Association |
| SARDA | South African Radio Drivers' Association |