rEnglishOxford New American Dictionaryr/ɑːr / ▸ abbreviation 1 recto. 2 (giving position or direction) right: l to r: Evan, Nick, and David. 3 Law rule: under r 7.4 (6) the court may hear an application immediately. ▸ symbol 1 radius: 2πr. 2 Statistics correlation coefficient: sigmoidoscopic and symptom scores also showed a significant correlation with each other (r = 0.91).