Somebody (pronoun)

1. A person, typically not specified or not known.
2. Some unspecified or unknown person.

Origin:

Middle english som body, from old english sum; see s(w)e- in indo-european roots.

Examples:

1. Somebody left their keys on the table.
2. I'm sure somebody will come to help us.
3. Somebody needs to take out the trash.
4. She's waiting for somebody to call her.
5. Somebody should have told me about the change.