noun

• (informal) A person who is very interested in a particular subject.
  "He’s a real history buff. He knows everything there is to know about the civil war."
• (video games, roleplaying games) An effect that makes a character or item stronger.
  "I just picked up an epic damage buff! Let's go gank the other team!"
• (rail transport) Compressive coupler force that occurs during a slack bunched condition.
• (colloquial) The bare skin.
  "to strip to the buff"

adj

• (originally bodybuilding, colloquial) Unusually muscular.
  "The bouncer was a big, buff dude with tattoos, a shaved head, and a serious scowl."
• (MLE slang) Physically attractive.
  "That's right: I'm taking driver's ed next semester. Hiring an interpreter for CHS and the deaf school outta my own hefty pockets. You're welcome. Oh, and I'm going to get really skinny and buff. All slim like a swimsuit model."

verb

• (video games, roleplaying games) To make a character or an item stronger.
  "The enchanter buffed the paladin to prepare him to fight the dragon."
• (medical slang) To modify a medical chart, especially in a dishonest manner.
  ""Sure thing, I buffed her, and they turfed her to urology, but she bounced back to me!" [...] They attempted to transfer her to urology by modifying her chart (buffing it) to request urine tests, but the doctors in urology sent (bounced) her back."
• (graffiti slang) To remove graffiti, particularly by someone who is not a graffiti writer.

noun

• (obsolete) A strike; a blow.
  "Nathless so sore a buff to him it lent / That made him reel."