Pro‐por″tion‐al (?), a. [L. proportionalis: cf. F. proportionnel.] 1. Having a due proportion, or comparative relation; being in suitable proportion or degree; as, the parts of an edifice are proportional. Milton.
2. Relating to, or securing, proportion. Hutton.
3. (Math.) Constituting a proportion; having the same, or a constant, ratio; as, proportional quantities; momentum is proportional to quantity of matter.
Proportional logarithms, logistic logarithms. See under Logistic. — Proportional scale, a scale on which are marked parts proportional to the logarithms of the natural numbers; a logarithmic scale. — Proportionalscales, compasses, dividers, etc. (Draughting), instruments used in making copies of drawings, or drawings of objects, on an enlarged or reduced scale.