noun

• (nautical) The upper spar used to control a gaff-rigged sail.
• (LGBTQ) A type of tight, panty-like underwear worn to hold the penis and testicles tucked backwards and make one's genital region look smooth, as if one had a vulva.
  "This may sound strange to readers who know little about nudes but many female impersonators, or femme-mimics, work au naturel—except for a gaff, a bra, body makeup, jewelry, and a wig (on their head). See! Semi-nude!!"

verb

• (transitive) To doctor or modify for deceptive purposes.
  "When the operator began losing, he gaffed the wheel and then the patron had no chance to win. With his secret device an experienced grifter could stop the wheel at will on any number."
• (slang, obsolete) To gamble, especially by tossing coins.
• (transitive, informal) To affix gaffer tape to, or cover with gaffer tape.
  "I gaffed down the sleeves to my lens hoods instead of just relying on the drawstring to hold it in place."

noun

• (dated) An outcry; nonsense.

noun

• (Ireland; British, especially Dublin, Manchester, MLE, Cockney and Glaswegian; slang) A place of residence.
  "We're going round to Mike's gaff later to watch the footie."
• (UK, slang, dated) A disreputable, low-end theatre.
  "Significantly, the setting is a gaff, a low, illegal theatre, and not one of the legitimate East-End stages."