* The act of screaming: "The child's scream startled everyone."
* The sound of screaming: "The scream echoed through the empty hallways."
* A loud, high-pitched cry: "He let out a scream of pain."
However, it's less common to use "scream" as a noun than as a verb. It's generally more natural to say "a loud scream" or "a scream of terror" rather than just "a scream."