Wiktionary
n. The culmination of a series of final matches played between a number of sporting teams
Wikipedia
A grand final is a game that decides a sports league's championship (or premiership) winning team, i.e. the conclusive game of a finals (or play-off) series. Synonymous with a championship game in North American sports, grand finals have become a significant part of Australian culture. The earliest competitions to feature a grand final were Australia's AFL (Australian rules football) and NRL (rugby league football). They influenced other competitions such as soccer's A-League, the National Basketball League, netball's ANZ Championship and European rugby league's Super League to adopt grand finals as well. Most grand finals involve a prestigious award for the player voted best on field.
Usage examples of "grand final".
This is a country, after all, where the grand final of a programme like Mastermind is frequently won by cab drivers and footplatemen.