'ambassiate' originates from Medieval Latin, specifically the word 'ambassiata,' where 'ambass-' referred to 'ambassador' and '-iate' was a suffix denoting office or function.

'ambassiata' transformed into the Old French word 'ambassade,' and eventually became the modern English word 'ambassiate' through Middle English.

Initially, it meant 'the office or function of an ambassador,' but over time it evolved into its current meaning of 'embassy.'