| Religious denominations in Poland | Regional rail | Reizei |
| Republic of Ireland | Religion in India | Relativist fallacy |
| Relation (mathematics)In mathematics an n-ary relation (or often simply relation is a generalization of binary relations such as " " and "<" which occur in statements such as "5 < 6" or "2 + 2 4". It is the fundamental notion in the relational model for databases. Formally, a | Recapitulation theoryOntogeny recapitulates phylogeny", also called the "biogenetic law" or the theory of recapitulation , is a now discredited hypothesis in biology first espoused in 1866 by Ernst Haeckel. Ontogeny is the development of the embryos of a given species; phylog | RecreationTigers playing in the water Recreation is the employment of time in a non-profitable way, in many ways also a refreshment of one's body or mind. Recreation is often distinguished from leisure. Where leisure is, or ought to be, restful, recreation is refre |
| RecessionA recession is usually defined in macroeconomics as a fall of a country's Gross National Product in two successive quarters. This is a simplified version of that of the business-cycle dating committee of the National Bureau for Economic Research, a U. | RecursionIn mathematics and computer science, recursion is a particular way of specifying (or constructing) a class of objects (or an object from a certain class) with the help of a reference to other objects of the class: a recursive definition defines objects in | ReptileCrocodilia Crocodilians Rhynchocephalia Tuataras Squamata Suborder Sauria Lizards Suborder Serpentes Snakes Testudines Turtles Superorder Dinosauria Saurischia Ornithischia The reptiles are a group of vertebrate animals. Most reptiles are tetrapods, and t |
| ReligionReligion sometimes used interchangeably with faith, is commonly defined as belief concerning the supernatural, sacred, or divine, and the practices and institutions associated with such belief. Borobudur, a Buddhist stupa built between 750 and 850 Adriaen | Reed CollegeReed College is a liberal arts college with about 1300 students as of 2004, located in Portland, Oregon in the quiet Eastmoreland neighborhood. Reed College Established 1908 School type Private Liberal Arts President Colin Diver Location Portland, OR, USA | Reductio ad absurdumReductio ad absurdum ( Latin for "reduction to the absurd", traceable back to the Greek ἡ εις το αδυνατον απαγωγη, "reduction to t |
| Reversible error | Retronym | Renaissance Classicism |
| Republic of Texas | Redneck | Regina |
| Reduction | Reverse engineering | Rebuttal |
| Res ipsa loquitur | Reich | Reggae |
| Relay league | Research | René Descartes |
| Renaissance | Republic | Request for Comments |
| Religious conversion | Rescuing Prometheus | Reunion |
| REM | Rectum | Religious Society of Friends |
| Reframing | Red Army | Relative frequency |
| Research subject | Revising opinions in statistics | Real number |
| Refreshable Braille display | Regular expression | Red Dwarf |
| Regex | Regular language | Reference work |
| Real Irish Republican Army | Republic of China | Rerun |
| Resistor | Republicanism | Repetitive strain injury |
| Real-time computing | Render farm | Render |
| Renewable energy | Revolver | Reykjavík |
| Retrovirus | Reincarnation | Religion and mythology |
| Red | Retention | Renaissance music |
| Recusancy | Regular grammar | REXX |
| Refactoring | Relational database | Refractive index |
| Resolutions of the Geneva International Conference | Ren and Stimpy | Reinhard Heydrich |
| Red Cross | Regiomontanus | Renaissance dance |
| Rem Koolhaas | Renzo Piano | Refraction |
| Recreational drug use | Revolution | Red Army Faction |
| Reign of Terror | Reliabilism | Reversi |
| Regular semantics | Read-only memory | Reciprocating engine |
| Register | Red Shift | Receptive aphasia |
| Rehoboam | Reloading | Relationship |
| René Magritte | Reform Judaism | Reconstructionist Judaism |
| Religion and homosexuality | Revelation | Red Hat Linux |
| Revolutionary Association of the Women of Afghanistan | Red Wolf | Real ale |
| Red Brigades | Revolutionary Armed Forces of Colombia | Remembrance of the dead - The Netherlands |
| Real Yellowwood | Real-time operating system | Rendering |
| Record | Reo | Rehavam Zeevi |
| Real Time Streaming Protocol | Real-time Transport Protocol | René Laënnec |