A painter of wall paintings.

Any wall painting may be called a *mural*. Murals have been around since long before the framed painting. Scenic murals date back to at least 2000 B.C. on the island of Crete. Indoor murals for private homes were popular in ancient Greece and Rome, and many of those at Pompeii were preserved by the lava of Mt. Vesuvius. In the Renaissance the muralists Raphael and Michelangelo created great wall and ceiling paintings for the Catholic Church, and Leonardo da Vinci's *The Last Supper* became one of the most famous of all murals. Mural painting saw a great revival in Mexico beginning in the 1920s, when a group of muralists inspired by the Mexican Revolution, including Diego Rivera, J. C. Orozco, and D. A. Siqueiros, began taking their intensely political art to the public by creating giant wall paintings, sometimes on outdoor surfaces.

Existing or occurring within the bounds of an institution, especially a school.

With its Latin prefix *intra-*, “within” (not to be confused with *inter-*, “between”), *intramural* means literally “within the walls.” The word is usually used for sports played between teams made up only from students at one campus. Intramural athletics is often the most popular extracurricular activity at a college or university.

Existing outside or beyond the walls or boundaries of an organized unit such as a school or hospital.

*Extramural* contains the Latin *extra-*, meaning “outside” or “beyond” (see EXTRA). The walls in *extramural* are usually those of schools, colleges, and universities, and the word is often seen in phrases like “extramural activities” and “extramural competition,” referring to things that involve the world beyond the campus. Some institutions use the term “extramural study” for what others call “distance learning”—that is, teaching and learning by means of Web connections to the classroom and to videos of lectures. Money that flows into universities to support research (from foundations, government institutes, etc.) is usually called “extramural income.”

To enclose within, or as if within, walls; imprison.

In Eastern European legend, whenever a large bridge or fort was completed, a young maiden would be immured in the stonework as a sacrifice. (It's not certain that such things were actually done.) In Poe's grim story “A Cask of Amontillado,” a man achieves revenge on a fellow nobleman by chaining him to a cellar wall and bricking him up alive. At the end of Verdi's great opera *Aida*, Aida joins her lover so that they can die immured together. But real-life examples of *immurement* as a final punishment are somewhat harder to find.

(1) Cleverly tactful. (2) Wise in promoting a plan or plan of action.

Politic behavior in class always requires a respectful attitude toward your teacher. It's never politic to ask for a raise when your boss is in a terrible mood. And once teenagers learn to drive, they quickly learn the politic way to ask for the car—that is, whatever gets the keys without upsetting the parents. As you can see, *politic* can be used for many situations that have nothing to do with public *politics.*

To give a political tone or character to.

Sexual harassment was once seen as a private matter, but in the 1980s and '90s it became thoroughly politicized, with women loudly pressuring lawmakers to make it illegal. So, at the same time, the issue of sexual harassment politicized many women, who began to take an interest in political action because of it. In other words, we may speak of an issue becoming politicized, but also of a person or group becoming politicized.

The high, fortified part of a city, especially an ancient Greek city.

The Greek root *acro-* means “high”; thus, an acropolis is basically a “high city.” Ancient cities often grew up around a high point, in order that they could easily be defended. The Greeks and Romans usually included in their acropolises temples to the city's most important gods; so, for example, Athens built a great temple on its Acropolis to its protector goddess, Athena, from which the city took its name. Many later European cities cluster around a walled castle on a height, into which the population of the city and the surrounding area could retreat in case of attack, and even South American cities often contain a similar walled area on high ground.

(1) A very large city. (2) A thickly populated area that includes one or more cities with the surrounding suburbs.

A “large city” named Megalopolis was founded in Greece in 371 B.C. to help defend the region called Arcadia against the city-state of Sparta. Though a stadium seating 20,000 was built there, indicating the city's impressive size for its time, Megalopolis today has only about 5,000 people. Social scientists now identify 10 megalopolises in the U.S., each with more than 10 million people. The one on the eastern seaboard that stretches from Boston to Washington, D.C., where the densely populated cities seem to flow into each other all along the coast, is now home to over 50 million people. But it's easily surpassed by the Japanese megalopolis that includes Tokyo, with more than 80 million inhabitants.