| Acronym | Meaning |
| R5 | Region 5 (DVD region) |
| RA | Resident Advisor Resident Assistant |
| RAC | Rock Against Communism |
| RAK | Random Act of Kindness |
| RAM | Random Access Memory |
| RAOK | Random Act Of Kindness |
| RAS | Remote Access Server |
| RATM | Rage Against the Machine (band) |
| RAWL | Roll Around While Laughing |
| RAWR | Right Answer, Wrong Reason |
| RBAY | Right Back At You |
| RBG | Revolutionary But Gangsta |
| RBTL | Read Between The Lines |
| RBV | Red Bull and Vodka |
| RC | Random Chat Radio Controlled |
| RCT | Roller Coster Tycoon |
| RD | Real Deal |
| RDC | Really Don’t Care |
| RDH | Rate Date Hate |
| RDJ | Robert Downey Jr. |
| RDM | Random Death Match |
| RDO | Regular Day Off |
| RDR | Red Dead Redemption (Game) |
| RFC | Request For Comment |
| RFI | Request For Information |
| RFID | Radio Frequency Identification |
| RFP | Request for Proposal |
| RFQ | Request For Quotation |
| RFT | Right First Time |
| RFTS | Reach For The Stars |
| RFYL | Run For Your Life |
| RGB | Red, Green, Blue |
| RHCP | Red Hot Chili Peppers (Band) |
| RHD | Right Hand Drive |
| RHI | Rumour Has It |
| RHIP | Rank Has Its Privileges |
| RHS | Right Hand Side |
| RINO | Republican In Name Only |
| RIYL | Recommended If You Like |
| RL | Real Life |
| RLAB | Roll Like A Buffalo |
| RLF | Real Life Friend |
| RLTW | Rangers Lead The Way |
| RMA | Return Merchandise Authorization |
| RME | Rolling My Eyes |
| RML | Read My Lips |
| RMT | Real-Money Trading |
| RMV | Results May Vary |
| RN | Right Now Registered Nurse |
| RNA | Ribonucleic Acid |
| RNB | Rhythm And Blues |
| RNG | Random Number Generator |
| RNR | Rock ‘N Roll |
| RO | Ragnarok Online ( ) |
| ROAR | Right Of Admission Reserved |
| ROFC | Rolling On Floor Crying |
| ROFL | Rolling On Floor Laughing |
| ROFLMFAO | Rolling On Floor Laughing My F***ing A** Off |
| ROFLOL | Rolling On Floor, Laughing Out Loud |
| ROG | Really Old Git |
| ROH | Ring of Honor (wrestling) |
| ROI | Return on Investment |
| ROLF | Rolling On Laughing Floor |
| ROR | Raughing out Roud |
| ROS | Right On Schedule |
| ROTC | Reserve Officer Training Corps |
| ROTF | Rolling On The Floor (laughing is implied) |
| ROTFFNAR | Rolling On The Floor For No Apparent Reason |
| ROTFL | Rolling On The Floor Laughing |
| ROTFLOL | Rolling On The Floor Laughing Out Loud |
| ROTGL | Rolling On The Ground Laughing |
| ROTK | Return of the King (Tolkien) |
| ROTM | Run Of The Mill |
| ROV | Remotely Operated Vehicle |
| ROW | Rest Of the World |
| ROY | Relative of yours? |
| RPC | Role Playing Chat |
| RPF | Real Person Fiction |
| RPG | Rocket Propelled Grenade Role Playing Game |
| RPM | Revolutions Per Minute |
| RPS | Rock Paper Scissors (game) |
| RQ | Random Questions (Livejournal community) |
| RSI | Repetitive Strain Injury |
| RSN | Real Soon Now |
| RSPB | Royal Society for the Protection of Birds |
| RSPCA | Royal Society for the Prevention of Cruelty to Animals |
| RSS | Rich Site Summary Really Simple Syndication |
| RSVP | Repondez s’il vous plait (Please reply) |
| RT | Retweet Real Time |
| RTA | Road Traffic Accident |
| RTB | Return To Base |
| RTD | Ready To Drink |
| RTF | Return The Favour |
| RTFAQ | Read The FAQ |
| RTFD | Read The F***ing Description |
| RTFI | Read The Flipping Instructions |
| RTFM | Read The Flipping Manual |
| RTFT | Read The F***ing Thread Read The F***ing Topic |
| RTG | Ready To Go |
| RTM | Read The Manual |
| RTO | Radio Telephone Operator |
| RTR | Roll Tide Roll |
| RTS | Real Time Strategy |
| RTV | Rock The Vote |
| RTW | Ready To Wear Round The World |
| RV | Recreational Vehicle |
| RVB | Red Versus Blue (popular web-series) |
| RVR | Realm Versus Realm ( ) |
| RW | Read-Write |
| RWD | Rear Wheel Drive |
| RWL | Roaring With Laughter |
| RWNJ | Right Wing Nut Job |
| RWP | Random Wall Post |
| RWYS | Reap What You Sow |
| RYC | Regarding Your Comment |
| RYN | Read Your Note Regarding Your Note |
| RYO | Roll Your Own |