'antinepotic' originates from modern English, specifically the prefix 'anti-' (from Greek 'anti' meaning 'against') combined with the element 'nepotic' drawn from 'nepotism,' which ultimately comes from Latin 'nepos' meaning 'nephew'.

'nepotism' came into English via French/Italian (e.g. French 'népotisme', Italian 'nepotismo') from Latin 'nepos'. The adjective form 'nepotistic' and related compounds in English made possible the later formation of 'antinepotic' by adding the productive prefix 'anti-'.

Initially terms derived from Latin 'nepos' referred specifically to nephews or kin; over time 'nepotism' came to mean favoritism shown to relatives in general. 'Antinepotic' therefore developed to mean 'against that practice' and retains that specific opposed-to-favoritism sense.