R

R is the eighteenth letter of the Latin alphabet.

Semitic Rêš (the head) developed into Greek Ρω (Rô). The sound value /r/ however was maintained in Greek as well as Etruscan and Latin.

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z

R is also:

• In organic chemistry, the symbol for the hydrocarbon chain.
• A rating given for films given by the Motion Picture Association of America, see R (rating)
• The stock symbol for Ryder Systems Inc.[?]
• A statistical programming language; see R (programming language)[?]
• The symbol used to represent the set of real numbers. Commonly displayed in the blackboard bold font.