'revenge-seeker' is formed from 'revenge' + 'seeker'. 'revenge' comes into English via Old French (e.g. 'revengier' / 'revenche') meaning 'to avenge', and 'seeker' is derived from the Old English verb 'sēċan' meaning 'to seek'.

The element 'revenge' entered Middle English from Old French (Middle English 'revenge'), while 'seek' (Old English 'sēċan') produced agentive forms such as 'seeker' in later Middle and Early Modern English; the compound 'revenge-seeker' developed by combining the noun 'revenge' with the agent noun 'seeker'.

Originally 'revenge' referred to the act of avenging; 'seek' meant to look for or pursue. Over time the compound came to mean 'a person who actively pursues vengeance' as a stable descriptor.