'acclivity' originates from Latin, specifically the word 'acclīvitās,' where 'ad-' meant 'toward' and 'clīvus' meant 'slope.'

'acclīvitās' transformed into the French word 'acclivité,' and eventually became the modern English word 'acclivity' through Middle English.

Initially, it meant 'an upward slope,' and this meaning has largely remained the same in modern usage.