noun
buff
BUHF/bʌf/
A knowledgeable and enthusiastic admirer of a subject.
The railway buff studies the model locomotive with knowledgeable delight.

Etymology
Buffalo-hide leather gave its name to the color of New York volunteer firefighters’ uniforms. That uniform association led to buff meaning an enthusiast—the sense used for someone devoted to a subject.
In context
you're a huge history buff. So, how did you decide to marry your love of history
More examples
- Two film buffs debated the ending.
- She is a history buff.
- The museum attracts aviation buffs.
Forms
buff · buffs
Similar words
- enthusiast
- Enthusiast is neutral and broader.
- aficionado
- Aficionado emphasizes informed appreciation.