Synonym of BUFF

Slave : (especially in the past) a person who is the legal property of another and is forced to obey them.
Enthusiast : a person who is very interested in a particular activity or subject.
Clown : a comic entertainer, especially one in a circus, wearing a traditional costume and exaggerated make-up.
Simpleton : a foolish or gullible person.
Buff : a person who is enthusiastically interested in and very knowledgeable about a particular subject.

Synonym of Buff is Enthusiast