The antonyms for "most rootless" are "most grounded" or "most stable". An individual who is grounded has a strong connection to their values, beliefs, and purpose in life. They are steadfast and secure in their decisions and have a deep sense of inner security. On the other hand, someone who is rootless lacks stability and consistency, wandering without direction and purpose. By embracing the concept of being grounded, individuals can develop a sense of stability that can help them weather the storms of life with confidence, while feeling connected and secure in their decisions.