Where does “anti-riot” come from?

anti-riot (English) comes from English riot, from Middle English riot, from Old French riote, from Latin rugiō, from Proto-Indo-European h₁rewg- — to belch; to roar.

Ancestry of “anti-riot”, step by step

anti-riot traces back through two separate lines of ancestry.

via English riot

StepLanguageWordMeaning
1EnglishriotWanton or unrestrained behavior; uproar; tumult;...
2Middle Englishriotdebauched living, dissipation
3Old Frenchriotequarrel; debate
4Latinrugiōto roar, bellow; rumble
5Proto-Indo-Europeanh₁rewg-to belch; to roar

via English anti

StepLanguageWordMeaning
1EnglishantiOpposed to something; That has a torsion angle...
2Englishanti-Against, hostile to; Contrasting with the norm;...
3Ancient Greekἀντι-anti-, against; like, reminiscent of
4Ancient Greekᾰ̓ντῐ́opposite
Every word from Proto-Indo-European h₁rewg- →Every word from Latin rugiō →Every word from Old French riote →