R
Abbreviation with 14 meanings
| Stands for | Republican (party label) |
|---|---|
| Meanings | 14 |
| Categories | Government & Politics, Units & Measurements, Arts & Entertainment, Geography & Places, Business & Finance, Texting & Internet Slang, Sports, Law & Legal, Religion |
| Also written | r, R. |
R has 14 meanings. The most common are Republican (party label) (political) and Pearson correlation coefficient (statistics); it can also stand for Restricted, River, Real numbers, Thursday (schedule code) and South African rand, plus 7 more listed below.
Meanings of R at a glance
| # | R stands for | Context |
|---|---|---|
| 1 | Republican (party label) | Government & Politics › Political |
| 2 | Pearson correlation coefficient | Units & Measurements › Statistics |
| 3 | Restricted | Arts & Entertainment › Film, Television and Theater |
| 4 | River | Geography & Places › Geographic Feature |
| 5 | Real numbers | Units & Measurements › Math |
| 6 | Thursday (schedule code) | Units & Measurements › Day of the Week |
| 7 | South African rand | Business & Finance › Currency |
| 8 | Are | Texting & Internet Slang › Texting and Chat |
| 9 | Runs | Sports › Baseball |
| 10 | Rex or Regina (the King or the Queen) | Law & Legal › Latin Legal |
| 11 | Rabbi | Religion › Religious Title |
| 12 | Degree Rankine | Units & Measurements › Engineering Unit |
| 13 | Ronna- (10^27) | Units & Measurements › Metric and SI Unit |
| 14 | Ronto- (10^-27) | Units & Measurements › Metric and SI Unit |
1. Republican (party label)
Government & Politics · Political Abbreviations
Single-letter label for the Republican Party used after politicians' names in news copy and election results, often combined with a state abbreviation, as in "Sen. John Doe, R-Ohio" or "(R-TX)".
Example: The bill passed with support from 12 senators, including Sen. Ortiz, R-Fla.
AP style pairs the party letter with the AP state abbreviation, as in "R-Fla.", while government websites usually use postal codes such as "R-FL". Election maps show Republicans in red, a convention television networks settled on around the 2000 election. Republicans are also known as the GOP.
2. Pearson correlation coefficient (r)
Units & Measurements · Statistics Abbreviations
A number from −1 to 1 measuring the strength and direction of the linear relationship between two variables. A value of 0.8 indicates a strong positive relationship, while values near 0 indicate little linear association.
Example: Hours studied and exam score were moderately correlated, r(98) = .46, p < .001.
Karl Pearson developed it in the 1890s from ideas of Francis Galton. Correlation does not imply causation, and r captures only linear association: a perfect U-shaped relationship can give r near 0. APA style reports r without a leading zero, because it cannot exceed 1, and puts degrees of freedom in parentheses. Squaring r gives R².
3. Restricted
Arts & Entertainment · Film, Television and Theater Abbreviations
MPA film rating meaning viewers under 17 must be accompanied by a parent or adult guardian. R films may contain strong language, violence, drug use, nudity or sexual content.
Example: Rated R for strong violence and language throughout.
Theaters enforce R-rating admission policies voluntarily, and some chains require ID. R-rated films such as The Matrix and Deadpool have been major hits despite limiting their young audience. The age threshold was 16 at the rating's 1968 launch and was raised to 17 in 1970.
4. River (R.)
Geography & Places · Geographic Feature Abbreviations
Abbreviation of River on maps, in atlases and footnotes, placed after the name in North American usage (Hudson R.) and before it in British usage (R. Thames).
Example: The trail follows the east bank of the Delaware R. for six miles.
British rivers are named River Thames and River Severn, so R. comes first; American rivers put River after the name. USPS uses RIV for River in street names.
5. Real numbers
Units & Measurements · Math Abbreviations
All points on the number line, rational and irrational, form the set written R or ℝ, including numbers such as π and the square root of 2. Calculus, analysis and physics are built on it.
Example: The function f(x) = x² is defined for all x in R.
R² and R³ denote the plane and three-dimensional space, as in "a vector in R³". Georg Cantor proved in 1874 that the reals are uncountable, so there are strictly more reals than rationals. LaTeX produces the blackboard-bold symbol with \mathbb{R}.
6. Thursday (schedule code)
Units & Measurements · Day of the Week Abbreviations
Many US college registrars use R for Thursday so that it cannot be confused with T for Tuesday. A class listed TR meets on Tuesday and Thursday.
Example: BIO 210 lecture TR 9:30 to 10:45; lab R 2:00 to 4:50.
The letter comes from the R sound in thuRsday, since T was taken by Tuesday; a few systems use H instead. The convention appears in course catalogs and student information systems across many US universities, often in the sequence MTWRF. New students frequently find it confusing, so schedules usually include a legend.
7. South African rand
Business & Finance · Currency Abbreviations
The local symbol for the South African rand, placed before the amount, as in R250, throughout South Africa and in neighboring Common Monetary Area countries.
Example: The ride from the airport to the city center was about R350.
The ISO code is ZAR. R also appears in the symbol for the Brazilian real (R$), so international documents prefer codes. Rand banknotes issued since 2012 feature a portrait of Nelson Mandela.
8. Are
Texting & Internet Slang · Texting and Chat Abbreviations
Single-letter homophone shortcut for "are," as in "r u ok?" Common in SMS-era texting, when each letter cost several key presses on a phone keypad.
Example: R u coming to the party or not? Need a head count.
Like U (you), it saves keystrokes but looks informal and dated. Younger users more often type the full word, and autocorrect may change it. Avoid in professional writing, where it suggests carelessness.
9. Runs
Sports · Baseball Abbreviations
Number of times a player crosses home plate safely, or a team's total score. In a box score's linescore, R appears beside H (hits) and E (errors).
Example: Linescore: Yankees R 5, H 9, E 1; Red Sox R 3, H 7, E 0.
Rickey Henderson holds the career record with 2,295 runs scored. A run counts only if the runner touches all bases in order and the third out is not made on a force play or by the batter before reaching first. Scoring runs is partly a team stat, since it depends on hitters behind the runner.
10. Rex or Regina (the King or the Queen) (R.)
Law & Legal · Latin Legal Abbreviations
Designates the Crown as prosecuting party in criminal cases, and as nominal party in judicial review, in England, Wales and other Commonwealth countries, as in "R v Smith". The letter means Rex during a king's reign and Regina during a queen's, so it never needs updating.
Example: In R v Brown, the House of Lords held that consent was no defense to the assaults charged.
Read aloud as "the Crown against Smith" in criminal cases. Judicial review cases take the form "R (on the application of X) v Secretary of State", shortened to "R (X) v ...". Canada uses the same convention in criminal cases. In US captions the prosecuting party is the People, State, Commonwealth or United States instead.
11. Rabbi (R.)
Religion · Religious Title Abbreviations
Abbreviation for rabbi in Jewish scholarly writing, especially before the names of sages quoted in the Mishnah and Talmud, such as R. Akiva or R. Yohanan. In modern use, "Rabbi" is usually written in full before a rabbi's name.
Example: The Mishnah quotes R. Akiva as saying that all is foreseen, yet freedom of choice is given.
In Hebrew texts, rabbinic names are often abbreviated with initials, as in Rashi (Rabbi Shlomo Yitzchaki) and Rambam (Rabbi Moshe ben Maimon). AP style uses "Rabbi" before a full name on first reference and the surname alone afterward. The Aramaic form Rav is used for Babylonian sages.
12. Degree Rankine
Units & Measurements · Engineering Unit Abbreviations
An absolute temperature scale with Fahrenheit-sized degrees, starting at absolute zero: 0°R is −459.67°F and water freezes at 491.67°R. Some US thermodynamics, aerospace and power-engineering calculations use it.
Example: Convert 70 F to about 530 R before applying the ideal gas law.
Scottish engineer William John Macquorn Rankine proposed the scale in 1859; it plays the same role for Fahrenheit that the kelvin plays for Celsius. Usage has declined as US engineering moves to SI, but older steam tables still use it. The Rankine cycle, the basis of steam power plants, also bears his name.
13. Ronna- (10^27)
Units & Measurements · Metric and SI Unit Abbreviations
Adopted in November 2022 at the 27th General Conference on Weights and Measures, ronna- denotes 10^27. Earth's mass is almost exactly 6 ronnagrams, the example the BIPM used to introduce it alongside quetta-, ronto- and quecto-.
Example: Under the 2022 prefixes, Earth's mass can be written as about 6 Rg.
The new prefixes were prompted largely by data science, where projections of global storage were approaching the yottabyte range. Names were chosen to avoid letters already used as unit symbols, and R and Q were among the few still free. The name loosely echoes Greek ennea, nine, since 10^27 is 1000^9.
14. Ronto- (10^-27) (r)
Units & Measurements · Metric and SI Unit Abbreviations
Introduced in 2022 together with quecto-, ronna- and quetta-, ronto- denotes 10^-27. An electron's mass is just under 1 rontogram, about 0.91 rg.
Example: An electron's mass is roughly 0.91 rg in the newest SI prefixes.
The 27th CGPM adopted it in November 2022, the first expansion of the prefix list since 1991. Like all submultiple prefixes it has a lowercase symbol. The name loosely derives from Greek ennea, nine, as 10^-27 is 1000^-9.
Related abbreviations
More political abbreviations
- POTUS – President of the United States
- PR – Proportional representation
- Prop – Proposition
- PVI – Partisan Voting Index
- RBG – Ruth Bader Ginsburg
- RCV – Ranked-choice voting
- Rep. – Representative
- RFK – Robert F. Kennedy
See all 91 political abbreviations →
More statistics abbreviations
- PPV – Positive predictive value
- Q1 – First quartile
- Q3 – Third quartile
- QQ – Quantile-quantile (plot)
- RMSE – Root mean square error
- ROC – Receiver operating characteristic
- RR – Relative risk
- RSS – Residual sum of squares
See all 88 statistics abbreviations →
This entry is for general education and is not legal advice. Abbreviation use varies between institutions; always confirm in context.