| Royal Flying Corps | Royal Flying Corps |
| Royal Flying Doctor Service | Royal Flying Doctor Service of Australia |
| Royal Jordanian | Royal Jordanian |
| Royal League | Royal League |
| Royal Mail Ship | Royal Mail Ship |
| Royal Marines | Royal Marines |
| Royal Mile | Royal Mile |
| Royal Monetary Authority of Bhutan | Royal Monetary Authority of Bhutan |
| Royal Navy | Royal Navy |
| Royal Opera House | Royal Opera House |
| Royal Pavilion | Royal Pavilion |
| Royal Shakespeare Theatre | Royal Shakespeare Theatre |
| Royal Society | Royal Society |
| royalty | royalty |
| Royan | Royan |
| Royat | Royat |
| Royston Drenthe | Royston Drenthe |
| Rozay-en-Brie | Rozay-en-Brie |
| rozzamente | coarsely |
| rozzezza | roughness |
| rozzissimo | crasser |
| rozzo | gross |
| Roßdorf | Roßdorf |
| Roßhaupten | Roßhaupten |
| Roßtal | Roßtal |
| Roşia Montană | Roşia Montană |
| Rožaje | Rožaje |
| RPG | IBM RPG |
| RPK | RPK |
| RPM Package Manager | RPM Package Manager |
| rRagnatela | web |
| rRNA | rRNA |
| Rrok Kola Mirdita | Rrok Mirdita |
| RS | RS |
| RSA | RSA |
| RSA Factoring Challenge | RSA Factoring Challenge |
| RSA Security | RSA Security |
| RSS | RSS |
| RSS Armena | Armenian SSR |
| RSS Azera | Azerbaijan SSR |
| RSS Bielorussa | Byelorussian SSR |
| RSS Carelo-Finlandese | Karelo-Finnish SSR |
| RSS Estone | Estonian SSR |
| RSS Georgiana | Georgian SSR |
| RSS Kazaka | Kazakh SSR |
| RSS Kirghiza | Kyrgyz SSR |
| RSS Lettone | Latvian SSR |
| RSS Lituana | Lithuanian SSR |
| RSS Lituano-Bielorussa | Lithuanian-Belorussian Soviet Socialist Republic |
| RSS Moldava | Moldavian SSR |
| RSS Tagica | Tajik SSR |
| RSS Tagika | Tajik SSR |
| RSS Turkmena | Turkmen SSR |
| RSS Ucraina | Ukrainian SSR |
| RSS Uzbeka | Uzbek SSR |
| RSSA di Mari | Mari Autonomous Soviet Socialist Republic |
| RSSA Karakalpaka | Karakalpak Autonomous Soviet Socialist Republic |
| RSSF Russa | Russian SFSR |
| RSSF Transcaucasica | Transcaucasian SFSR |
| RSVP | R.S.V.P. |
| RT | RT |
| RTEMS | RTEMS |
| RTFM | RTFM |
| RTL Group | RTL Group |
| RTTI | Run-time type information |
| RTVE | RTVE |
| RTÉ | Radio Telefís Éireann |
| RU | Moisture storage |
| RUA | Rugila |
| Ruanda | Rwanda |
| ruba | thieves |
| rubacchiare | steal |
| rubare | run away with |
| rubare la scena | steal the show |
| rubata | stolen |
| rubato | stolen |
| Rubber | Rubber |
| Rubbiatron | Energy amplifier |
| Rubcovsk | Rubtsovsk |
| Ruben | Reuben |
| Ruben Berrios | Rubén Berríos |
| Ruben Boumtje Boumtje | Ruben Boumtje-Boumtje |
| Ruben Sosa | Rubén Sosa |
| Rubens Barrichello | Rubens Barrichello |
| rubeola | rubella |
| ruberia | larceny |
| Rubeus Hagrid | Rubeus Hagrid |
| Rubiaceae | Rubiaceae |
| Rubiales | Rubiales |
| rubicondo | ruddy |
| Rubicone | Rubicon |
| rubidio | rubidium |
| Rubielos de Mora | Rubielos de Mora |
| Rubigen | Rubigen |
| rubinetto | tap |
| rubinetto di arresto | stopcock |
| rubino | jewel |
| Rubiá | Rubiá |
| rublo | ruble |
| Rublo bielorusso | Belarusian ruble |
| Rublo russo | Russian ruble |
| Rublo sovietico | Soviet ruble |
| Rublo transnistriano | Transnistrian ruble |
