The Big Gold Belt is a slang term used to designate the design of the NWA/WCW/WWE World Heavyweight Championship Belt. The name derivates from the fact that, at the time, it was physically the largest professional wrestling championship title belt, and its design was all-gold.
The Big Gold Belt is the only major championship in professional wrestling that does not have a company/promotion designation anywhere on it.
The belt itself has been used to represent several championships, including:
The WCW World Heavyweight Championship 1991 (WCW declared that the belt represented their World Heavyweight Champion, which was unified with the NWA's - The man holding the belt was the "Real World Champion," as he held the world titles of two promotions. When Ric Flair went to the WWF in late 1991, following a dispute with the WCW/NWA office, he took the belt with him, and the WWF began promoting him as the "Real World's Champion," complete with the Big Gold Belt on WWF Television. Oops!)
The WCW International World Heavyweight Championship 1993 (When Ric Flair returned to WCW, they had established a new design to represent the World Championship, and made up a story that the Big Gold Belt was representative of the top champion in a subsidiary of the company called WCW International.)
The WCW World Heavyweight Championship again, in 1994 (Ric Flair defeated Rick Rude to unify the WCW World Heavyweight Championship and the WCW International World Heavyweight Championship. WCW International was never mentioned again.)
One-Half of the WWF/WWE Undisputed Championship 2001-2002 (Chris Jericho defeated The Rock and Stone Cold Steve Austin on the same night to win the WCW and WWF Championships, unifying them to the WWF Undisputed Championship. When the WWF changed their name to the WWE, the title became the WWE Undisputed Championship.)
The WWE World Heavyweight Championship 2002-2003 (when Brock Lesnar signed an exclusive deal with the WWE's Smackdown! brand, the Big Gold Belt was awarded to Triple H to represent the WWE World Heavyweight Championship.)
Some argue that the Big Gold Belt includes the legacies of all of these championships, as a straight line can be drawn from champion to champion. Other declare that each designation the belt is only a symbol, used to represent each of the six championships it was symbolic of.