Select the most appropriate word for the given group of words.

A person who has had long experience in a particular field

Veteran

The most appropriate word for the given group of words is veteran.

• Veteran means "a person who has had long experience in a particular field".
• Amateur means "a person who engages in a pursuit, especially a sport, on an unpaid rather than a professional basis".
• Cosmopolitan means "having a broad, international outlook".
• Stoic means "able to endure pain or hardship without showing your feelings or complaining".