'arrogant' originates from Latin, specifically the word 'arrogans' (present participle of 'arrogare'), where 'ad-' meant 'to' and 'rogare' meant 'to ask, propose'. The English noun element '-ness' comes from Old English '-nes(s)e' used to form abstract nouns.

'arrogant' passed into English from Old French 'arrogant' (from Latin 'arrogans'), and English later formed the abstract noun by adding the native suffix '-ness', producing 'arrogantness' as a derived noun (alongside the more common 'arrogance').

Initially it meant 'claiming or taking for oneself (presumptuously)' in Latin; over time the sense narrowed to 'showing superiority or self-importance', which is the modern meaning.