'assiduity' originates from Latin, specifically the word 'assiduitas,' where 'assiduus' meant 'constant or persistent.'

'assiduitas' transformed into the Old French word 'assiduité,' and eventually became the modern English word 'assiduity' through Middle English.

Initially, it meant 'constant presence or attendance,' but over time it evolved into its current meaning of 'diligence or perseverance.'