1informal A thing, especially a blow, which causes a person's nose to bleed by its violence.
2US informal A seat high up in an auditorium or stadium.
3A person with a nosebleed; a person prone to bleeding from the nose. Also figurative (specifically in Basketball, slang).
1920s; earliest use found in Henry Williamson (1895–1977), writer. From nosebleed + -er.