'assiduous' originates from Latin, specifically the word 'assiduus,' where 'assid-' meant 'to sit near or beside.'

'assiduus' transformed into the French word 'assidu,' and eventually became the modern English word 'assiduous' through Middle English.

Initially, it meant 'to sit near or beside,' but over time it evolved into its current meaning of 'showing great care and effort.'