'reflectivity' originates from the Latin word 'reflectere,' where 're-' meant 'back' and 'flectere' meant 'to bend.'

'reflectere' transformed into the French word 'réfléchir,' and eventually became the modern English word 'reflect' through Middle English.

Initially, it meant 'to bend back,' but over time it evolved into its current meaning of 'the property of reflecting light or other radiation.'