'archdiplomatist' originates from English, specifically a compound of the prefix 'arch-' (meaning 'chief' or 'principal') and 'diplomatist' (a form of 'diplomat' with the agentive suffix '-ist'), where 'arch-' meant 'chief' and 'diplomatist' indicated 'one skilled in diplomatic affairs'.

'diplomatist' is derived from 'diplomat', which entered English via French 'diplomate' from Late Latin 'diploma' and Greek 'diplōma' meaning 'a folded paper/document'; the modern compound 'archdiplomatist' is a recent English coinage formed by prefixing 'arch-' to the existing agent noun.

Initially formed to mean 'the chief or foremost diplomat', the term has also taken on a broader, figurative sense of 'a supreme negotiator or conciliator in any sphere' over time.