'essentialness' originates from Latin, specifically the word 'essentia' and the adjective 'essentialis', where the root 'esse' meant 'to be'.

'essentialness' changed from Middle English 'essential' (borrowed from Old French 'essentiel' from Latin 'essentialis') and eventually became the modern English noun 'essentialness' by the addition of the suffix '-ness'.

Initially, it meant 'having the nature of being (something necessary or fundamental)', but over time it developed into the specific noun meaning 'the quality or state of being essential'.