Changeless means it seems never to change. Mountains, the sea in a certain light, a habit that has been the same for fifty years — that is the kind of thing people call changeless. It is a quieter, more bookish word than “the same” or “unchanged”. Unchanged usually means “not different from before, this time”; changeless paints a bigger picture, as if the thing does not know how to be different. You will meet it in stories and careful description more than in chat. Nobody says “my changeless password”. Though actually, even the people who use it know that few things are truly without change — the word is often a feeling, not a science claim.

不變的、看來永不改變的（偏書面）