'enlighten' originates from the prefix 'en-' (from Old French/Latin influence) combined with the base 'lighten', which comes from Old English 'līhtan'/'lihtan' meaning 'to make light'.

'enlighten' developed in Middle English as a combination of 'en-' + 'lighten' and eventually became the modern English verb 'enlighten' meaning to give light (literal) and, later, to give understanding (figurative).

Initially, it meant 'to make light' in a literal sense; over time it evolved into figurative senses such as 'to give intellectual or spiritual light' and now commonly means 'to give knowledge or understanding'.