Roos - San
- Roosevelt Corollary
- Roosevelt Dam
- Roosevelt Island
- Roosevelt, Anna Eleanor
- Roosevelt, Franklin Delano (FDR)
- Roosevelt, Theodore (Teddy)
- root beer
- Root, Elihu
- Root, John Wellborn
- Root-Takahira Agreement
- Rose
- Rose Bowl
- Rose City
- Rosebud Reservation
- Rosebud, Battle of the
- Rosecrans, William Starke
- Rosenberg Case
- Rosenberg case
- Rosenwald, Julius
- Ross, Betsy
- Ross, Diana
- Ross, Edward Alsworth
- Ross, Elisabeth Griscom (Betsy Ross)
- Ross, Harold Wallace
- Ross, John
- Ross, Nellie
- Rostovtzeff, Michael Ivanovich
- Rostow, Walt Whitman
- Rotarian
- Rotary Club
- Rotary International
- ROTC
- Rothko, Mark
- rotten borough
- Rough Riders
- Roughriders
- round
- round lot
- round robin
- round steak
