| Africa |
Africa is one of the seven largest areas of land on the earth. These areas of land are called continents. Africa is the second largest continent on our planet. Only Asia is bigger than Africa. Africa is made up of more than fifty different countries, and people speak many different languages in these countries. Some of the languages are Swahili, Hausa, and Arabic. |
| air |
the mixture of gases that surrounds the earth. Air is made up of oxygen, nitrogen, and other gases, and has no taste, odor, or color. [1/6 definitions] |
| alien |
from a planet other than Earth; extraterrestrial. [1/5 definitions] |
| altitude |
the height of a thing above earth or above sea level. |
| ancestor |
An ancestor is a living thing from a very long time ago that is related to a living thing that is on the earth now. Over time, many changes occurred to the ancestor so that it developed into the living thing that it is now. [1/2 definitions] |
| Antarctica |
Antarctica is one of the seven largest areas of land on the earth. These areas of land are called continents. The continent of Antarctica is very cold all year round. |
| anthill |
a pile of earth made by ants as they dig their underground nest. Anthills are found near the nest entrance. |
| archaeological |
Something that is archaeological has something to do with archaeology. Archaeology is the study of human life a very long time ago. People who study archaeology dig up ancient things from the earth, such as pottery, tools, and even buildings. Then they study these things to understand how people lived very long ago |
| archaeology |
Archaeology is the study of human life a very long time ago. People who study archaeology dig up ancient things from the earth, such as pottery, tools, and buildings. Then they study these things to understand how people lived very long ago. |
| arctic |
When we talk about the Arctic region or Arctic winds or Arctic seas, we are talking about the area of the world that is farthest north and very cold. The North Pole is at the center of the Arctic region of the earth. The word "Arctic" can be spelled with a capital letter at the beginning or not. [2/3 definitions] |
| Arctic Circle |
an imaginary line drawn around the earth parallel to the equator which marks the boundary of the Arctic. North of this line there are periods of continuous night in the winter and continuous day in the summer. |
| Arctic Ocean |
The Arctic Ocean is one of the five oceans of the world. An ocean is a large body of salt water that covers a very large part of the earth. The Arctic Ocean is in the most northern part of the world and it is very cold and icy. If you look at a map, it is above Canada, Russia, and other far northern countries of the world. |
| Asia |
Asia is one of the seven largest areas of land on the earth. These areas of land are called continents. Asia is the largest of all the seven continents on our planet. Many different languages are spoken in Asia. Some of them are Chinese, Japanese, Hindi, Bengali, Farsi, and Arabic. |
| astronomer |
a scientist who studies the universe beyond the earth. |
| astronomy |
the branch of science that studies the universe beyond the earth. |
| Atlantic Ocean |
The Atlantic Ocean is one of the five oceans on our planet. An ocean is a large body of salt water that covers a very large part of the earth. It is much bigger than a sea or lake. If you want to travel from America to Africa or Europe, you have to cross the Atlantic Ocean. |
| atmosphere |
the gases surrounding the earth or other similar objects in outer space. [1/3 definitions] |
| atmospheric |
of, relating to, or made of the gases that surround the earth. |
| Australia |
Australia is a country but it is also a continent. A continent is one of the seven largest areas of land on the earth, like North America, Africa, or Asia. Most continents are made up of many countries, but Australia is both a continent and a single country. Australia is famous for its unusual animals, such as the kangaroo and the koala. These animals only live in Australia except if they live in a zoo. Australia is the smallest of all the continents, but it is still very large! [1/2 definitions] |
| bacteria |
microscopic organisms that often play a role in the decay of living things, the process of fermentation, and sometimes in causing disease. Bacteria are each made up of only one cell, but different kinds of bacteria can take different shapes. These organisms live in all parts of the earth including oceans, deserts, glaciers, hot springs, and in the bodies of most living things. While some kinds of bacteria are dangerous, most kinds are useful because they help in the digestion of food, in the making of soil, in the creation of medicines, and in many other natural processes. |
| bacterium |
singular form of "bacteria." Bacteria are tiny living things made up of one cell each. Bacteria live in most living things and in all parts of the earth. Most bacteria are useful to people, but some are harmful because they can cause disease. |