| Abbreviation | Definition |
|---|---|
| RPU | Rainbow Pride Union |
| RRFCU | Red River Federal Credit Union |
| RRWU | Rhodesian Railway Workers' Union |
| RTAM | Retired Teacher's Association of Manitoba |
| RTUF | Railway Trade Unions Federation |
| RU | Russian Union |
| RUB | Reeve Union Board |
| RUB | Reitz Union Board |
| RUCC | Regional Union Construction Center |
| RUDL | Rugby Union Dunkerque Littoral |
| RUEA | Republican Union of Employers of Armenia |
| RUEBU | Russian Ukrainian Evangelical Baptist Union |
| RUFT | Rescue Union Federation of Teachers |
| RUHS | Redford Union High School |
| RUIS | Revolutionary Union for Internationalist Solidarity |
| RUJ | Russian Union of Journalists |
| RUPA | Rugby Union Players' Association |
| RUSD | Reed Union School District |
| RUSG | Royale Union Saint Gilloise |
| RUSU | Reading University Students Union |