x_{1} (set) and x_{2} (set) are sets which have non-empty mutual intersection and mutual relative complements (set subtraction; both orders of operands/directions considered); id est: x_{1} and x_{2} share at least one element, but also have a mutual symmetric difference such that neither is a subset of the other.

In other words, each of these following three sets is nonempty: x_{1 \setminus x}, and x_{2 \setminus x}, and the intersection of x_{1} with x_{2}. There is no word/terminology in English for this concept, to krtisfranks' knowledge. x_{1} and
x_{2} are mutually symmetric terbri under transposition with one another. The empty set and a universal set are disallowed for x_{1} (thus also x_{2}). If x_{1 }= x_{2}, then x_{1} na klesrverlapi x_{2} (emphasis on "na"). This word encompasses the sets which are shown as circles in the traditional Venn diagram.