'soporific' originates from Latin, specifically the word 'soporificus,' where 'sopor' meant 'deep sleep' and '-ficus' meant 'making or causing.'

'soporificus' transformed into the French word 'soporifique,' and eventually became the modern English word 'soporific' through Middle English.

Initially, it meant 'causing deep sleep,' and this meaning has largely remained the same in modern usage.