'arrogate' originates from Latin, specifically the word 'arrogare', where 'ad-' meant 'to, toward' and 'rogare' meant 'to ask, propose'.

'arrogate' passed from Latin 'arrogare' into Late Latin and Old French forms (e.g. 'arroger') and then into Middle English, eventually forming modern English 'arrogate' and related derivatives like 'arrogatingly'.

Initially related to 'asking' or 'proposing' (through 'rogare'), the sense shifted toward 'claiming for oneself' or 'appropriating' without right; this evolved into the modern meaning of 'to take or claim (something) presumptuously', hence 'arrogatingly' = 'in a claiming/presumptuous manner'.