The Free On-line Dictionary of Computing (30 December 2018):

Axiom of Comprehension

    An axiom schema of set theory which states:
   if P(x) is a property then

   	x : P

   is a set.  I.e. all the things with some property form a set.

   Acceptance of this axiom leads to Russell's Paradox which is
   why Zermelo set theory replaces it with a restricted form.

   (1995-03-31)