All abbreviations starting with R
| Term | Full Form | Category |
|---|---|---|
| R | Angle of Reflection 
| Others |
| R | Are
| Others |
| R | combined hormonal vaginal ring
| Others |
| R | Ideal Gas Constant (8.314 joules per Kelvin)
| Others |
| R | Rabbi
| Others |
| R | Rabbit
| Others |
| R | Rabid
| Others |
| R | Rabies
| Others |
| R | Race
| Others |
| R | Racer
| Others |
| R | Racial
| Others |
| R | Racing
| Others |
| R | Racism
| Others |
| R | Rack
| Others |
| R | Radfahrabteilung (German Bicycle Battalion, World War II)
| Others |
| R | Radial
| Others |
| R | Radiancy
| Others |
| R | Radians
| Others |
| R | Radiation
| Others |
| R | Radical
| Others |
| R | Radius
| Others |
| R | Rail
| Others |
| R | Railroad
| Others |
| R | Rain
| Others |
| R | Raise
| Others |
| R | Rally
| Others |
| R | Ralphable
| Others |
| R | Ramming
| Others |
| R | Rand
| Others |
| R | Rand (South Africa)
| Others |
| R | Random
| Others |
| R | Randy
| Others |
| R | Range
| Others |
| R | Range Rate
| Others |
| R | Rank
| Others |
| R | Rankine
| Others |
| R | Rankine Temperature Scale
| Others |
| R | Rare
| Others |
| R | Rarity
| Others |
| R | Rate
| Others |
| R | Rates
| Others |
| R | RATFOR (short for Rational Fortran) file
| Others |
| R | Ratio
| Others |
| R | Rational
| Others |
| R | Rationality
| Others |
| R | Rationing
| Others |
| R | Raw
| Others |
| R | Ray
| Others |
| R | Re-bill
| Others |
| R | Re-tell
| Others |