(1) A decorative garden with paths between the beds of plants. (2) The back area of the ground floor of a theater, often under the balcony.

*Parterre* comes to English by way of French, where it means “on the ground.” And in the early years of the theater, the parterre was truly on the ground. In Shakespeare's day, an English theater's parterre was the cheap standing-room area right in front of the stage, normally filled with rowdy spectators. The original idea of the French parterre garden, with its carefully designed plots and walkways, was to present an artistic pattern when seen from above—from a balcony, a raised terrace, or the top of an outdoor staircase. English gardeners responded with garden designs that tried to make their viewers half-forget that they were seeing something created by humans rather than untamed nature itself.

Underground.

A tunnel is a subterranean road or pathway, and a subway is a subterranean railway. The subterranean vaults at Fort Knox hold billions of dollars of gold reserves. Subterranean reservoirs called *aquifers* are tapped for water; in places where the pressure on the subterranean water is great enough, a hole drilled in the ground will bring it bubbling to the surface.

The turtle exhibit at a zoo is often in the form of a terrarium, as are some of the exhibits at a plant conservatory. In an ant terrarium, elementary-school students watch the ants dig their network of tunnels as if no one were watching. Terrariums try to create conditions as close as possible to a natural habitat. A covered terrarium can often sustain itself for months on the moisture trapped inside. But creating a good terrarium requires careful control not only of humidity but also of temperature, as well as good ventilation; the lighting should include the full spectrum of sunlight as well as a day-night regulator.

(1) Having to do with Earth or its inhabitants. (2) Living or growing on land instead of in water or air.

Everything on or having to do with Earth can be called terrestrial. Mercury, Venus, and Mars are often called the terrestrial planets, since they are rocky balls somewhat like Earth rather than great globes of gas like Jupiter, Saturn, Uranus, and Neptune. Something *extraterrestrial* comes from beyond the earth and its atmosphere; the word can be used to describe anything “out of this world,” from moon rocks to meteors. Turning to the second sense of *terrestrial*, animals are often divided into the terrestrial (land-living) and the aquatic (water-living). And sometimes terrestrial animals are contrasted with *arboreal* animals, those that live in trees.

A dock or harbor where pleasure boats can be moored securely, often with facilities offering supplies or repairs.

*Marina* comes straight from Latin, where it means simply “of the sea.” At a modern marina, sailors can acquire whatever they need for their next excursion, or they can tie up their boats until the next weekend comes along. Some even imitate John D. MacDonald's famous detective hero Travis McGee, who lives on his boat in Miami and rarely leaves the marina.

(1) A transparent blue or blue-green gem. (2) A pale blue or greenish blue that is the color of clear seawater in sunlight.

*Aqua marina* is Latin for “seawater,” so when a lovely blue-green form of the semiprecious gem known as beryl was given an English name several centuries ago, *aquamarine* seemed appropriate. Aquamarine is the ideal color that most of us carry around in our heads when we imagine the waters that lap the shores of the Greek and Caribbean islands on a sunny day. But even the Mediterranean and the Caribbean can take on lots of other colors depending on weather conditions.

A seaman or sailor.

In Coleridge's *Rime of the Ancient Mariner,* an old seaman tells of how, by shooting a friendly albatross, he had brought storms and disaster to his ship, and how as punishment his shipmates hung the great seabird around the mariner's neck and made him wear it until it rotted. The word *mariner* has occasionally been used to mean simply “explorer,” as in the famous Mariner spaceflights in the 1960s and '70s, the first to fly close to Mars, Venus, and Mercury.

(1) Bordering on or having to do with the sea. (2) Having to do with navigation or commerce on the sea.

The maritime countries of Portugal and England produced many seafaring explorers during the 16th and 17th centuries, many of whom sailed under the flags of other countries. Sailing for the Spanish, Ferdinand Magellan captained the ship that was the first to circle the world, charting many new maritime routes as it went. Henry Hudson, funded by the Dutch, sailed up what we call today the Hudson River, claiming the maritime area that now includes New York City for the Netherlands.