An udder is the part of the female cow or goat that milk comes from. Baby cows or goats drink from their mother's udder, but people also collect the milk using machines so they can sell it in shops.

Photo by Valerie Everett

UFO stands for unidentified flying object. Usually when people say UFO or flying saucer they mean a visiting alien spaceship. Most UFO sightings are eventually identified to be something ordinary, like a weather balloon, an ordinary airplane or a strange cloud.

Photo by SantaRosa OLD SKOOL

A ukelele is a small, four-stringed member of the guitar family. Ukuleles come in four sizes: soprano, concert, tenor, and baritone. They can be played by plucking or strumming them.

Photo by Lorena Cupcake

An ultrasound is a medical scan that uses soundwaves to "see" what is happening inside you. Ultrasounds are most often used to look at unborn babies while they are developing.

Photo by Myllissa

An umbrella is a portable shelter that is used for keeping off the rain. Some people also use umbrellas to shelter them from the sun. Small umbrellas that are mainly for keeping off the sun are called parasols.

Photo by D Sharon Pruitt

Something is under something else if it is lower than it.
This cat is under the chair.

The opposite of under is over.

Photo by Curran.kelleher

A unicycle is a bicycle with only one wheel. The "uni" at the start of the word means one, just like the "bi" on bicycle means two, and the "tri" on tricycle means three.

Because unicycles only have one wheel they are hard to ride and hard to steer, and they are not seen very often outside of circuses.

Photo by Euthman

A university is a place where people go, usually after finishing school, to learn more about something so they can get a job. Universities give you a degree or some other certification when you have finished learning. In some countries, a place where you go for other kinds of tertiary education is known by other names, like a college or a techical school.

Photo by Sk12

Up is a direction. You go up when you go higher. The person in the picture has just climbed up the ladder and is now sitting at the top. The opposite of up is down.

Photo by Sara. Nel

You are upside-down when your head is lower than your feet. You can go upside-down hanging from play equipment like monkey bars, or if an adult holds you up by your feet. The world looks different when you are upside-down.

When you turn anything else the wrong way up you say it is upside-down. Cats often lie upside-down with their legs in the air.

Photo by Johnny Jet