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.
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.
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.
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.
The umbilical cord connects a developing baby to its mother, via the placenta. The umbilical cord has veins and arteries in it that carry blood between the baby and its mother.
The umbilical cord usually falls off not long after the baby is born.
