| universe |
The universe is everything that exists, including the earth, planets, and stars. |
| university |
A university is a large school where students can go after high school. |
| unless |
When you say you are going swimming today unless it rains, it means that rain is the only reason you might not go swimming. |
| untie |
When you tie a knot, you make a knot in something. When you untie a knot, you make it loose until there is no more knot. |
| until |
If you play until dinner is ready, you play before dinner and then stop playing when dinner is ready. [3 definitions] |
| unusual |
When something is unusual, it does not happen very often, or we don't see it often. |
| up |
When you go up, you move to a higher place. When an airplane goes up, it goes from the ground into the sky, or it goes from one place in the sky to a higher place. [8 definitions] |
| upon |
When you put you hand upon your head, you put your hand on your head. |
| upset |
When you are upset, you are angry or sad or very worried about something. [3 definitions] |
| upside down |
When something is upside down, it means that the part that is usually on the top is on the bottom. |
| upstairs |
When you go upstairs, you go to a higher floor in a building. When your room is upstairs, it means that your room is on a higher floor. |
| Ural Mountains |
The Ural Mountains are a long range of mountains in Russia. The Ural Mountains make a natural border between the continent of Europe and the continent of Asia. The Ural Mountains are home to bears, wolves, foxes, lynxes, and many other animals. |
| Uranus |
Uranus is a large, round object out in space. Like Earth, it is a planet that goes around the sun. Uranus is very cold. It is far from the sun and travels around it very slowly. It take 84 earth years for Uranus to travel around the sun just once. |
| urban |
Urban things are things that have to do with the city or life in the city. Another way to describe a city is to call it an urban area. Urban areas are very different from places in the country. The buildings are very close together, and there are many stores, restaurants, and other businesses. In an urban place, most people live in apartments instead of in houses. |
| Urdu |
Urdu is the language of Pakistan and one of the languages of India. Urdu is spoken like another major language of India called Hindi, but Urdu is written in a different way and has some different words. |
| Uruguay |
Uruguay is a country in South America. It is on the coast of the Atlantic Ocean between Brazil and Argentina. Uruguay has plains and low hills and beaches. Many people raise sheep and cattle in Uruguay, but most people live and do jobs in the cities. |
| us |
If you say "come with us," you are asking someone to come with you and someone else. |
| use |
When you use a thing, you do something with it and it helps you do something that you want to do. When you eat, you often use a fork or spoon. When you paint, you use a brush. [3 definitions] |
| used |
When something is used, it was owned by someone else before now. It is not new. [2 definitions] |
| useful |
When something is useful, you can use it in good ways. |
| useless |
When something is useless, it can't do anything good for you. |