'costliness' originates from Middle English, specifically the word 'costlynesse,' where 'costly' meant 'expensive' and '-ness' was a suffix forming nouns.

'costlynesse' transformed into the modern English word 'costliness' through the addition of the suffix '-ness' to 'costly'.

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