One who riots; part of the unruly violent crowd causing a riot.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "rioter" in a sentence
"III. v.68 (338,2) a sworn rioter] A _sworn rioter_ is a man who practises riot, as if he had by an oath made it his duty."
"As soon as I and a few others arrived I clearly recall a rioter hurling abuse at us as well as missiles."
"Just after finishing the note directly below, I received this email from reader Keivan -- one sign, at least, of people seeing through the "rioter" PR strategy:"