'vengeance-seekers' originates from Modern English, formed by compounding the noun 'vengeance' and the agent noun 'seeker'; 'vengeance' ultimately comes from Old French 'vengeance', from Latin 'vindicantia' (related to 'vindicare'), where 'vindicare' meant 'to claim, avenge', and 'seek' comes from Old English 'sēcan' meaning 'to seek'.

'vengeance' passed from Latin 'vindicare' → Old French 'vengeance' → Middle English 'vengeance'; 'seek' developed from Old English 'sēcan' → Middle English 'seken' → modern 'seek', and the agentive suffix '-er' formed 'seeker'. The compound 'vengeance-seeker' is a modern English formation (appearing in 19th–20th century English usage) and the plural 'vengeance-seekers' follows regular pluralization.

Initially, the separate elements meant 'retribution' (vengeance) and 'one who looks for something' (seeker); combined they have retained the clear meaning 'a person who seeks retribution' into modern usage.