'lightness' originates from Old English, specifically the word 'lēohtnes,' where 'lēoht' meant 'light' and '-nes' was a suffix forming nouns.

'lēohtnes' transformed into the Middle English word 'lightnesse,' and eventually became the modern English word 'lightness'.

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