x1 (li) is an extremal bound (supremum/infimum/possibly-unattained extremum (loose sense in English)/asymptote (one sense)/best possible bound (one sense)) on set x2 (set) in direction x3 (li) in ordered structure x4; x1 bounds x2 tightly/maximally-strongly from the x3 side in x4; x2 is bounded from the x3 side by x1 and any other bound on that side is worse than is x1.
x1 need not be finite. Many of the notes to zmaumce apply to this word, with minor appropriate edits. praperi modifying this word means that x2 does not contain x1. If x1 does indeed belong to x2, then x1 is an attained extremum (maximum, minimum, vel sim.) of x2. The possible values of x1, and its existence at all, depends delicately on x4. This word allows for easy vagueness about which extremal bound is to be used. See also: mecraizmana'u (partial near-synonym), zmaraimecna'u (partial near-synonym).