Parasite single is a term used to talk about people who are adults, but still living with their parents or family.
When you're a kid, your parents take care of you and make sure you have everything you need, like food, clothes, and a place to live. But when you grow up, you're supposed to take care of yourself and make your own decisions.
Some people, however, choose to stay living with their parents even when they're grown up. This is called being a parasite single because they are kind of like a parasite that lives off their parents' resources without contributing much themselves.
Sometimes, these people might have jobs and make money, but they don't use that money to contribute to the household. Instead, they might use it to buy things for themselves or to go out with friends.
While it's okay to live with your parents for a little while after you become an adult, it's important to eventually start taking care of yourself and standing on your own two feet.