Boxer (noun)

1. A person who fights with their fists in a boxing match.
2. A person who is skilled in the sport of boxing.
3. A dog breed with a short, smooth coat and a powerful, muscular build, originally bred for hunting and fighting.

Origin:

Early 18th century: from box + -er.

Examples:

1. He became a professional boxer at the age of 22.
2. The boxer trained hard for the match.
3. He was a boxer in the Olympics.
4. She had a boxer dog named Max.
5. The boxer breed is known for its strength and agility.