Meaning of Boolean ring

Bool'ean ring'

Pronunciation: [key]
— Math. Math.
  1. a nonempty collection of sets having the properties that the union of two sets of the collection is a set in the collection and that the relative complement of each set with respect to any other set is in the collection. Cf. algebra of sets.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.