Origin: Latin prefix sub-
Subsidiarity has 2 different meanings across 1 category:
secondary importance
The principle that initiative (whether in government, business or religion) ought to reside at the lowest feasible level (i.e. at the local or regional level, instead of the national or supranational level, unless the latter presents clear advantages)
The word comes from the Latin subsidiarius, which originally meant serving as an aid or support. It entered English through a direct combination of the root "subsidiary" and the suffix "-ity".