axial

basic essential fundamental important key paramount pivotal significant

cardinal center chief dominant interior intermediate leading master mean median middle midway primary prime radical ruling salient umbilical

centric centroidal equidistant focal foremost inmost inner mid middlemost midmost nuclear omphalic outstanding overriding predominant

additional auxiliary extra inessential insignificant minor nonessential secondary trivial unimportant unsubstantial

exterior extreme inferior outer outside subordinate

peripheral