'archival' originates from English formation based on 'archive' + adjectival suffix '-al'. 'archive' ultimately comes from Greek, specifically the word 'arkheion', where 'arkhē' referred to 'rule' or 'office' (hence 'public records/office').

'archive' entered English via Old French/Medieval Latin from Greek 'arkheion'; the adjective 'archival' was formed in English by adding '-al' to 'archive', and 'archivally' is the adverbial form derived from 'archival'.

Initially related to the place or office of public records ('arkheion' = public office/records); over time it came to denote the records themselves and anything 'relating to archives', leading to the modern adjectival/adverbial sense 'relating to archives'.