If something is changeless, it's permanent, staying the same over time. Your dad's routine may seem changeless, identical day after day — until the morning he decides to start raising goats in your backyard.
Some things appear to be changeless, like the stars in the sky. Larger concepts are often described as changeless: your best friend might believe that morality is changeless, while you think that notions of right and wrong evolve over time. The adjective changeless is formed by adding the suffix -less, "lacking," to change, which comes from a Latin root meaning "to exchange."