'sadness' originates from Old English, specifically the word 'sædnes,' where 'sæd' meant 'sated, full' and '-ness' was a suffix forming nouns.

'sædnes' transformed into the Middle English word 'sadnesse,' and eventually became the modern English word 'sadness.'

Initially, it meant 'fullness or satisfaction,' but over time it evolved into its current meaning of 'a state of being unhappy or sorrowful.'