'scrupulous' originates from Latin, specifically the word 'scrupulosus,' where 'scrupulus' meant 'a small sharp stone or a source of uneasiness.'

'scrupulosus' transformed into the Old French word 'scrupuleux,' and eventually became the modern English word 'scrupulous' through Middle English.

Initially, it meant 'having moral integrity,' but over time it evolved into its current meaning of 'being very careful and thorough.'