'deceleration' originates from Latin, specifically the word 'decelerare,' where 'de-' meant 'down' and 'celerare' meant 'to hasten.'

'decelerare' transformed into the French word 'décélération,' and eventually became the modern English word 'deceleration' through Middle English.

Initially, it meant 'to slow down or reduce speed,' and this meaning has largely remained the same in modern usage.