Definition of "R"

R¹

letter
upper case, lower case r, plural Rs or R's
1. The eighteenth letter of the English alphabet, called ar and written in the Latin script.
number
upper case, lower case r
1. The ordinal number eighteenth, derived from this letter of the English alphabet, called ar and written in the Latin script.

R²

noun
1. (entomology) radius
2. (US, politics) Republican
3. (monarchy) rex (“king”) or regina (“queen”); the initial by which a British monarch signs documents after his or her name
4. (handbells) ring
5. (chess) rook
6. (baseball, cricket) runs, the statistic reporting the number of runs scored by a player
7. (law) the Crown, the government of a monarchy (abbreviating rex (“king”) or regina (“queen”))
8. (especially in university catalogs) Thursday
  Quotations
  Lecs, T R 9:05; lab, M T W R or F 1:25—4:25, or M or W 7:30—10:30 p.m.
  1986, Cornell University Courses of Study, page 250
  8:30 MWF (3 x 1 hour) […] 8:30-10 TR (2 x 1.5 hours)
  2000 August, M.W. Carter, “A Comprehensive Course Timetabling and Student Scheduling System at the University of Waterloo”, in Edmund Burke, Wilhelm Erben, editors, Practice and Theory of Automated Timetabling III, Springer, published 2001, page 66
  Office Hours: MTWRF: 9:00–11:00, 1:30–3:00 or stop by my office anytime.
  2007, W. Ted Mahavier, “Syllabus for Analysis” (Lamar University course syllabus), appendix II.A of Charles A. Coppin et al., The Moore Method: A Pathway to Learner-Centered Instruction, Mathematical Association of America (2009), page 201
adjective
1. (film certification) restricted
2. reverse
3. right (as opposed to left)
proper noun
1. (religion) In the context of the documentary hypothesis, the Redactor(s) who compiled and edited the Torah.
  Quotations
  One needs to be careful, however, to distinguish between original P and the work of the later priestly Redactor (R), who edited P and other documents in the postexilic period.
  2006, David Ringo Miano, Shadow on the steps‎ (dissertation), UC San Diego, page 5