'efflux' originates from Latin, specifically the word 'effluxus,' where 'ex-' meant 'out of' and 'fluere' meant 'to flow.'

'effluxus' transformed into the French word 'efflux,' and eventually became the modern English word 'efflux' through Middle English.

Initially, it meant 'to flow out,' and this meaning has largely remained the same in modern usage.