'anti-insurgent' is a compound of the prefix 'anti-' (from Greek 'antí' via Latin/Old French, meaning 'against') and 'insurgent' (from Latin 'insurgēns', present participle of 'insurgere', meaning 'rising up').

'insurgent' came into English from Latin 'insurgēns' (Late Latin/Medieval Latin 'insurgens'), through usage in later medieval and early modern periods, and developed into the modern English word 'insurgent'; the compound 'anti-insurgent' formed by combining 'anti-' + 'insurgent' in modern usage to denote opposition to insurgents.

Initially, 'insurgent' originally meant 'rising up' or 'one who rises against authority'; over time it became the standard term for 'rebel', and 'anti-insurgent' consequently came to mean 'against rebels' or 'opposed to insurgency'.