Something that's untrammeled is completely free and unrestricted. If you live a truly untrammeled life, you feel free to follow your dreams.
As opposed to a lion in a zoo, a wild animal is untrammeled, or free to roam. You could also describe a dictator's power as untrammeled, in a much less positive sense — he is free to make any laws he wants, and to treat his subjects however he chooses. Untrammeled comes from trammel, or "restriction," which also refers to a particular kind of fishing net. The root is Late Latin, tremaculum, "net made of three layers."