What does “only child” mean in English?

An only child is a person who has no brothers and no sisters. They are the only kid in the family. You can not work this phrase out word by word, so it is good to learn it as one set phrase. You say it about yourself like this: I’m an only child. That means you grew up with no brothers or sisters at home, just you and your parents.

In the clip, one person says: “Not really. I’m an only child.” This is a normal, polite way to answer the question “Do you come from a large family?” If you have no brothers or sisters, you simply say, I’m an only child.