Somebody means a person, but you don't know or don't need to say exactly who. When you tell your mom that somebody ate the last cookie, you're saying a person did it without naming them. When a teacher asks if somebody can help carry books to the library, they're looking for any willing person, not a specific student.

The word becomes more interesting when you use it to mean an important or notable person. When people say someone “is really somebody” or wants “to be somebody,” they mean a person who has achieved recognition or success. A young inventor who dreams of becoming somebody wants to be known and respected for their accomplishments. In this sense, somebody is the opposite of being just another face in the crowd.

You might hear people use it in questions: “Is somebody home?” or “Did somebody call my name?” The word works when the specific identity doesn't matter or isn't known yet.

Related words include someone, which means the same thing and can be used interchangeably. The opposite is nobody, meaning no person at all.