English
hemimetric
From hemi- + metric.
Today it means
noun An abstraction of distance; a function, d, with two arguments that satisfies d(x,x) = 0 and d(x, y) + d(y,z) ≥ d(x,z) (the triangle inequality) for all x,y,z in the domain.
Language periods are conventional ranges, not dates for this word.
Etymograph / hemimetric