• dree world,
• cree world,
• vree world,
• gree world,
• tree world,
• rree world,
• feee world,
• fdee world,
• ffee world,
• ftee world,
• f5ee world,
• f4ee world,
• frwe world,
• frse world,
• frde world,
• frre world,
• fr4e world,
• fr3e world,
• frew world,
• fres world

The adjective form of the phrase "free world" is "free-world".

The plural form of the word "free world" remains the same: "free world".

The singular form of the word "free world" is "free world". The term "free world" does not typically have a singular form because it is already a singular noun phrase.