To infect is to introduce a disease into a person or thing. When you infect yourself with a virus, you are putting yourself at risk for getting sick.
An intruder is someone who comes into your home or place of work without permission. They might be thieves, burglars, or anyone else who wants to cause trouble.
To infect something is to cause it to get sick or to have something bad happen to it. When you infect your computer with a virus, you're causing it to get infected with a virus.
When two or more things are clumped together, it means that they are all close to each other. This is often a sign that they are being squished or compressed.
To overwhelm something is to overcome it or to cause it to be defeated. When the protesters overwhelmed the police officers, they were able to win the battle.
To vaccinate is to give someone a vaccine. Vaccines are important because they help protect people from diseases.
To consign something is to put it in a designated place where it will be stored or used. When you consign a piece of furniture to the attic, you're telling the furniture that it's going to be stored there.