'plateau' originates from French, specifically the word 'plateau,' where 'plat' meant 'flat' and the suffix '-eau' formed a noun indicating a place or thing.

'plateau' entered English from French in the mid 17th century as 'plateau.' The French word itself developed from Old French elements related to 'plat' (flat), ultimately tracing back to Latin/Greek roots such as Greek 'πλατύς (platýs)' meaning 'broad' or 'wide.'

Initially, it referred specifically to 'a flat elevated area of land'; over time it broadened to the figurative sense of 'a stable or level condition after growth,' which is common in modern usage.