monist
/ˈmɑnɪst/
noun
- A person who believes that reality is made of only one kind of substance or principle (e.g., only matter or only spirit).
- The philosopher was a monist who argued that everything is made of energy.
- As a monist, she rejected the idea that mind and body are separate.
- The ancient Greek thinker Parmenides is often called a monist because he believed only one thing truly exists.