supremum

noun1

1. •
   (real analysis): Given a subset X of R, the smallest real number that is ≥ every element of X; (order theory): given a subset X of a partially ordered set P (with partial order ≤), the least element y of P such that every element of X is ≤ y.

   • A sublattice of a lattice is a subset that is closed under pairwise infima and suprema. — 2006