'archspy' originates from English, specifically the combining of the prefix 'arch-' (from Greek 'arkhē', meaning 'chief' or 'principal') and the word 'spy' (from Old French 'espier', meaning 'to watch' or 'look out'); here 'arch-' meant 'chief' and 'spy' meant 'one who watches or observes'.

'archspy' is a modern English compound formed by joining 'arch-' and 'spy'. The element 'arch-' comes into English via Late Latin/Greek ('arkhē' → 'arch-'), while 'spy' changed from Old French 'espier' into Middle English forms (e.g. 'spien') and eventually the modern English 'spy'; the compound itself has no long historical precedent and is a recent formation.

Initially the separate elements meant 'chief' (arch-) and 'to watch/observe' (spy); combined in modern usage they mean 'the chief watcher' or 'head spy', a sense that follows directly from the components.