'proportionality' originates from Latin, specifically the word 'proportionalitas,' where 'pro-' meant 'for' and 'portio' meant 'part or share.'

'proportionalitas' transformed into the Old French word 'proportionalité,' and eventually became the modern English word 'proportionality' through Middle English.

Initially, it meant 'the state of being in proportion,' and this meaning has largely remained the same in modern usage.