'ascriptitious' originates from Latin, ultimately from the verb 'ascribere' (a variant of 'ad-scribere'), where the prefix 'ad-' meant 'to/toward' and 'scribere' meant 'to write'.

'ascriptitious' developed via Late Latin/Medieval Latin formations related to 'ascriptio'/'ascriptitius' (meaning things that were written or assigned to someone) and was adopted into English in learned/antiquarian usage as 'ascriptitious'.

Initially it carried the sense 'written to' or 'registered/assigned' (i.e., literally 'written onto' a list or roll); over time it came to be used more broadly as 'attributed or ascribed' (not necessarily literally written).