Inverted Sixes is a term used in the game of bridge, referring to a bidding system where two sixes are bid in an inverted order. This means that the first six is bid at a higher level than the second six. The crossword solution for this term is NINES, which refers to the fact that the two sixes are bid as if they were nines. Inverted Sixes is a popular bidding system among bridge players, as it allows them to make more aggressive bids and increase their chances of winning the game.