Fixed futures refer to contracts or agreements that have predetermined terms and conditions, usually relating to financial investments or commodities. The antonyms, on the other hand, are variable, flexible, and unpredictable. Unlike fixed futures, variable futures refer to contracts that have changing terms and conditions, making them less restrictive and adaptable to evolving market conditions. Flexible futures, on the other hand, allow investors to modify their investment plans based on new information, trends, or events. Finally, unpredictable futures refer to investments that are subject to random fluctuations or unforeseeable events that can affect their value. In summary, the antonyms of fixed futures provide investors with more freedom, adaptability, and reduced risk.