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

'reflectere' transformed into the English word 'reflect,' and eventually became the modern English word 'reflectance' through the addition of the suffix '-ance.'

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