1. (a.) Having a due proportion, or comparative relation; being in suitable proportion or degree; as, the parts of an edifice are proportional.

2. (a.) Relating to, or securing, proportion.

3. (a.) Constituting a proportion; having the same, or a constant, ratio; as, proportional quantities; momentum is proportional to quantity of matter.

4. (n.) Any number or quantity in a proportion; as, a mean proportional.

5. (n.) The combining weight or equivalent of an element.

3-D affinitive analogical analogous appertaining associative balanced commensurable commensurate comparable comparative compatible congenial connective consistent contingent correlated correlative corresponding cubic dependent dimensional distributional distributive en rapport equal even stephen fifty-fifty flat fourth-dimensional half half-and-half halvers harmonious in accordance with linking particular per capita per head pertaining pertinent pro rata proportionable proportionate proportioned prorated reciprocal referable referring related relating relational relative respective several space space-time spatial spatiotemporal spherical stereoscopic superficial surface symmetrical sympathetic three-dimensional two-dimensional volumetric