WordNet sense 1 (exhibiting equivalence or correspondence among constituents of an entity or between different entities):

harmonious, symmetrical

WordNet sense 2 (being in a state of proper balance or equilibrium):

balanced

WordNet sense 3 (having a constant ratio):

proportional

WordNet sense 4 (properly related in size or degree or other measurable characteristics; usually followed by `to'):

relative

WordNet sense 5 (proportionate):

proportionable

WordNet sense 6 (agreeing in amount, magnitude, or degree):

corresponding, in proportion to

WordNet sense 7 (corresponding in size or degree or extent):

commensurate