/ ˈraɪətəs; NAmE / adjective [ usually before noun ]
1.
( formal or law ) noisy and/or violent, especially in a public place :
riotous behaviour
The organizers of the march were charged with assault and riotous assembly .
2.
noisy, exciting and enjoyable in an uncontrolled way
SYN uproarious :
a riotous party
riotous laughter
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WORD ORIGIN
Middle English (in the sense troublesome ): from Old French , from riote debate, from rioter to quarrel, of unknown ultimate origin.