'plunge' originates from Old French, specifically the word 'plongier,' where 'plong-' meant 'to sink or immerse.'

'plongier' transformed into the Middle English word 'plungen,' and eventually became the modern English word 'plunge.'

Initially, it meant 'to immerse or submerge,' but over time it evolved into its current meanings of 'to dive energetically' and 'to fall suddenly.'