'insincerity' originates from Latin, specifically the word 'insinceritas,' where 'in-' meant 'not' and 'sinceritas' meant 'purity or honesty.'

'insinceritas' transformed into the French word 'insincérité,' and eventually became the modern English word 'insincerity' through Middle English.

Initially, it meant 'lack of purity or honesty,' and this meaning has largely remained the same in modern usage.