Tomboy (noun)

1. A girl who behaves in a manner traditionally associated with boys, such as being interested in sports and other activities usually associated with boys.
2. A girl who is boyish in appearance or dress.

Origin:

From tom ("boy") + boy, from the practice of calling young girls who acted like boys "tom boys" in the 16th century.

Examples:

1. She was a tomboy as a child, preferring to play sports and hang out with the boys.
2. She was always mistaken for a boy, as she was a bit of a tomboy.
3. She was a tomboy and always enjoyed playing with boys' toys.
4. She was a tomboy who loved climbing trees and playing rough games.
5. The tomboy was always getting into trouble for climbing on the roof.