'indoctrinate' originates from Medieval Latin, specifically the word 'indoctrinare,' where 'in-' meant 'into' and 'doctrina' meant 'teaching.'

'indoctrinare' transformed into the French word 'endoctriner,' and eventually became the modern English word 'indoctrinate' through Middle English.

Initially, it meant 'to teach or instruct,' but over time it evolved into its current meaning of 'to teach someone to accept a set of beliefs uncritically.'