'unessentially' originates from the prefix 'un-' meaning 'not' and the word 'essential,' which comes from Latin 'essentialis,' meaning 'pertaining to essence.'

'essentialis' transformed into the Old French word 'essentiel,' and eventually became the modern English word 'essential.' The prefix 'un-' was added to form 'unessentially.'

Initially, 'essential' meant 'pertaining to essence,' but over time it evolved to mean 'absolutely necessary.' 'Unessentially' thus means 'not in an absolutely necessary manner.'