After reading this post What is the name for a function whose codomain and domain are equal?
I have two questions:
Is there a term for a binary function or operator: D×D-> D? In some sense, this could be considered a functional over D^2, although that doesn't seem very natural to me.
What about a unary function that is not endomorphic, we call such a function "non-endomorphic"?
A binary operation $D \times D \to D$ is often called a "multiplication". Importantly I would not call it a functional. In my mind a functional in this context would be a function expecting a function as input. I don't think there is a special word for a function $D \times D \to D$ like there is for an endomorphism.
For a unary function which is not endomorphic, that means it sends $A \to B$... We would just call this a function. If you wanted to emphasize that it is not an endomorphism, you could say that it is "non-endomoprhic" if you needed to.