'greenness' originates from Old English, specifically the word 'grēnnes,' where 'grēne' meant 'green' and '-ness' was a suffix indicating a state or quality.

'grēnnes' transformed into the Middle English word 'grēnnesse,' and eventually became the modern English word 'greenness'.

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