What is Object Eclipsing?

Question

This is the question that my interlocutor asked me. My answer -

if we assign an object of a derived class to a reference of the base class, the members of the derived class will darken or hide.

he did not say it wrong or right. I want to confirm this.

Answer 1

There is no such thing as "eclipse of an object."

Answer 2

Perhaps the interviewer wanted to say slicing ?

This, or it was a trick.