A buff is someone who has a strong, special interest in something.

VOA: special.2009.05.17

"Don't keep them away from something that can change their lives and give them a new vision and give their parents a new vision of them, just because they don't want someone in the community to say, 'oh,your child is special."

VOA: special.2009.08.23

But to be chosen by your peers, especially someone like me who has been to four Olympics, who grew up in Lake Placid , it's pretty special to be recognized in that capacity."

VOA: standard.2010.02.27