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.
You upturn something when you flip it upside down. Once you upturn something, it is upturned.
Uranus is the seventh planet from the sun. It takes 84 years to travel around the sun. Uranus is 2,870,972,200km from the Sun. Its radius is 25,559km.
A urinal is a toilet that is only used for urinating in. Urinals are usually found in men's bathrooms, and are designed for use by men. Men, of course, can urinate standing up. Women sit down.
An urn is a large vase. Urns are often seen outside in gardens as an ornament. Sometimes people grow plants in urns. Smaller urns are used to store ashes of people after they have been cremated. This kind of urn is often stored on people's mantelpieces.
Something is useless if there is no purpose for it. Something may become useless because it is broken and no longer does what it is supposed to do, or it might have never done anything to begin with.
Usual is another word for normal. When something is going along the way it always does, it is usual. For example, "his day was progressing as usual". The opposite of usual is unusual.