| radiator |
a device that uses steam or hot water passing through pipes in order to heat a room. [2 definitions] |
| radical |
having to do with the root or source; basic; fundamental. [4 definitions] |
| radii |
a plural of "radius." |
| radio |
a way of sending signals made of waves that travel through the air. These radio waves are picked up and translated into sounds by electronic devices. [3 definitions] |
| radioactive |
giving off energy as a result of the decay of unstable atoms. |
| radioactivity |
the giving off of energy as a result of the decay of unstable atoms. |
| radish |
a plant that has a crisp and strong-tasting root. [2 definitions] |
| radium |
a silver-white, radioactive metal that is one of the chemical elements. Radium glows in the dark. It is used to treat cancer. (symbol: Ra) |
| radius |
a straight line from the center to the edge of a circle or sphere. [2 definitions] |
| radon |
a radioactive gas that is one of the chemical elements. It is found in small amounts in some soils and rocks. (symbol: Rn) |
| raffle |
a game in which the person who has bought the ticket that is drawn wins a prize. [2 definitions] |
| raft1 |
a flat platform made of materials that can float, such as wood or barrels filled with air. Rafts are often used to carry people or goods. [3 definitions] |
| rag1 |
a scrap or small piece of cloth. [2 definitions] |
| rag2 |
(informal) to tease or scold. |
| rage |
extreme anger; fury. [3 definitions] |
| ragged |
worn down into rags; torn. [4 definitions] |
| ragtime |
a form of music developed in the late nineteenth and early twentieth century in America. Ragtime was a popular kind of music with a bouncy rhythm, usually written for the piano. |
| ragweed |
a weed that produces a large amount of pollen in the fall. Many people are allergic to ragweed. |
| raid |
a sudden, surprise attack. [3 definitions] |
| rail1 |
a bar of wood or metal that runs between two posts and serves as a fence or barrier. [3 definitions] |
| railing |
a barrier or fence made of posts and rails. [2 definitions] |