/ prəˈpɔːʃənl; NAmE -ˈpɔːrʃ-/ adjective
proportional (to sth) of an appropriate size, amount or degree in comparison with sth :
Salary is proportional to years of experience.
to be directly / inversely proportional to sth
► pro·por·tion·al·ly adverb :
Families with children spend proportionally less per person than families without children.
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WORD ORIGIN
late Middle English : from late Latin proportionalis , from proportio(n-) , from pro portione in respect of (its or a person's) share.