word 'not-being'?

THEAETETUS: Certainly we do.

STRANGER: Let us be serious then, and consider the question neither

in strife nor play: suppose that one of the hearers of Parmenides was

asked, 'To what is the term "not-being" to be applied?'--do you know

what sort of object he would single out in reply, and what answer he

would make to the enquirer?

THEAETETUS: That is a difficult question, and one not to be answered at

all by a person like myself.

STRANGER: There is at any rate no difficulty in seeing that the

predicate 'not-being' is not applicable to any being.

THEAETETUS: None, certainly.

STRANGER: And if not to being, then not to something.

THEAETETUS: Of course not.

STRANGER: It is also plain, that in speaking of something we speak of

being, for to speak of an abstract something naked and isolated from all

being is impossible.

Sophist