| Acronym | Meaning |
| RCCSD | (partially) Restricted CCSD |
| RCCSD | (spin) Restricted CCSD |
| RCF | Refractory Ceramic Fibers |
| RCF | Relative Centrifugal Force |
| RCF | Rolling Contact Fatigue |
| RCHF | Relaxed-core Hartree-Fock (approxn. In Calcns. On Mol. K-shell Excitation Spectra) |
| RCI | Relativistic Configuration Interaction |
| RCI | Restricted Configuration Interaction |
| RCIOSA | Reactive Classical-infinite-order-sudden Approxn. |
| RCIS | Resource Center Information System |
| RCISD | Restricted CI (with) Single (and) Double (excitations) |
| RCLED | Resonant Cavity Light Emitting Diode |
| RCM | Radiative Convective Model (of Climate) |
| RCM | Ring-closing Metathesis |
| RCM | Rotated-coordinate Method |
| RCNDO | Rydberg CNDO |
| RCNDO/S | Rydberg CNDO/screened |
| RCO | Regenerative Catalytic Oxidizer |
| RCP | Reciprocal Calcn. Procedure [of ACGIH] |
| RCP | Rapid Crack Propagation |
| RCP | Recursive Correlation Partitioning |
| RCR | Recrystallization Controlled Rolling |
| RCR | Replication-competent Retrovirus |
| RCR | Respiratory Control Ratio |
| RCRA | Resource Conservation And Recovery Act Of 1976 |
| RCRIS | Resource Conservation And Recovery Information System |
| RCS | Reaction Control System |
| RCS | Recoupled Centrifugal Sudden (approxn. |
| RCSB | Research Collaboratory For Structural Bioinformatics |
| RCSF | Reference Configuration-state Function |
| RCSI | Random Cooperative Strain Interaction |
| RCT | Reference Control Technology |
| RCTM | Regional Chemical Transport Model |
| RD | Remedial Design |
| RD/RA | Remedial Design/Remedial Action |
| RDA | Recommended Daily Allowance |
| RDA | Regularized Discriminant Analysis |
| RDA | Representational Difference Analysis |
| RDC | Rotating Disk Contactor |
| RDE | Rotating Disk Electrode |
| RDEQ | Reduced Dimensionality Exact Quantum (method For Reactive Scattering) |
| RDF | Radial Distribution Function |
| RDF | Refuse Derived Fuel |
| RDF | Restricted Dirac-Fock (quantum Calcn. Method) |
| RDGTO | (back-)rotated Distributed Gaussian-type Orbital |
| RDH | Rapid Displacement Heating (pulping - For Paper) |
| RDI | Reference Daily Intake |
| RDNP | Reverse Differential Normal Pulse |
| RDO | Reduced Density Operator |
| RDPP | Reverse Differential-pulse Polarography |