'subside' originates from Latin, specifically the word 'subsīdere,' where 'sub-' meant 'under' and 'sīdere' meant 'to settle.'

'subsīdere' transformed into the French word 'subsider,' and eventually became the modern English word 'subside' through Middle English.

Initially, it meant 'to settle or sink down,' but over time it evolved into its current meanings of 'becoming less intense' and 'sinking to a lower level.'