To teem is to be full of life, to be bustling with activity. When you see a teeming city, you can see people walking and shopping all around.
Spaceships are vehicles that are used to travel through space. They are usually made out of metal and plastic, and they are powered by engines.
When you say that someone has lived a lifetime, you are meaning that the person has been alive for a very long time. A lifetime can be defined in a number of ways, but the most common way to measure it is by how many years the person has been alive.
To harbor someone is to protect them and to allow them to stay in your country or place. You might harbor a fugitive, which is someone who is wanted by the government for a crime.
To harness something is to use it to help you achieve your goals. You might harness energy from the sun to power your house, or you might harness the power of the wind to drive your ship.
Doable means that something is possible and reasonable. It's usually used in a negative sense to describe something that is not very likely to happen.
To colonize is to take over a new area and make it part of your own country or empire. Sometimes this is done by force, but other times it is done by convincing the people there to join your country or empire.
When you breathe, you take in air through your nose and mouth. Air is essential for human life, and it's important to take it in regularly.
To vanish is to disappear completely. When the witch vanished, she disappeared from the town and everyone who was close to her lost track of her.