ˈzȯ(ə)rnz-, ˈtsȯ- noun
Usage: usually capitalized Z
Etymology: after Max August Zorn died 1993 American (German-born) mathematician
: a lemma in set theory: if S is partially ordered and if each subset for which every pair of elements is related by one of the relationships “less than,” “equal to,” or “greater than” has an upper bound in S, then S contains at least one element for which there is no greater element in S