proportional

Word family

• proportion
  nounB2
• proportionally
  adverbB2
• proportionate
  adjectiveC1
• disproportionate
  adjectiveC1
• disproportionally
  adverbC1

Synonym discussion

Sense: adjective/1

These words all describe a relationship of match or balance between things. 'Proportional' is the most neutral and mathematically precise, used when two quantities change by the same factor — double one and the other doubles. 'Proportionate' leans more formal and is common in legal or political writing, as in a proportionate response to a threat. 'Commensurate' is highly formal and suggests a fitting match, often between effort and reward or status and responsibility — 'a salary commensurate with experience.' 'Corresponding' is broader and less precise; it means things go together in some way, not necessarily by a fixed ratio. In everyday speech, use 'proportional' for numbers and measurements, and 'proportionate' for abstract concepts like justice or fairness.

Etymology

Proportional comes from Late Latin 'proportionalis', meaning 'relating to proportion'. The Latin root 'proportio' itself combined 'pro' ('for, in comparison with') and 'portio' ('portion, part'). The word entered English in the late 14th century through Old French, first used in mathematics and later extended to general contexts of balance and fairness.