What's the best name for a non-mutating “add” method on an immutable collection?

Question

Sorry for the waffly title - if I could come up with a concise title, I wouldn\'t have to ask the question.

Suppose I have an immutable list type. It has an operat

Answer 1

I would go for Add, because I can see the benefit of a better name, but the problem would be to find different names for every other immutable operation which might make the class quite unfamiliar if that makes sense.