Unknown. First appeared in print in 1980s, but probably existed before that. The most common theory for its origin is that a purchase (especially that of a full three-piece suit) from Montague Maurice Burton (1885-1952), founder of Burton Menswear, was known as a "full Monty". According to the OED, this etymology is "perhaps the most plausible".
- (UK) (colloquial) All inclusive; everything; a whole package.
- I thought he was only going to buy the basic kit, but he bought the full monty.
Usage notes 
Usually with the.
- "Full monty" in Michael Quinion, Ballyhoo, Buckaroo, and Spuds, 2004.