say it: pruh-pawr-shuh-NAL-i-tee
proportionality is a noun meaning "a ratio of two quantities that is constant". It carries 2 recorded senses.
a ratio of two quantities that is constant
harmonious arrangement or relation of parts or elements within a whole (as in a design)
“in all perfectly beautiful objects there is found the opposition of one part to another and a reciprocal balance”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for proportionality come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.