protester
US /ˈproʊ.tes.tɚ/
UK /ˈproʊ.tes.tɚ/

1.
manifestante, protestante
a person who publicly demonstrates strong objection to something or expresses dissent, often as part of a group
:
•
The police arrested several protesters at the demonstration.
A polícia prendeu vários manifestantes na demonstração.
•
She joined the group of environmental protesters.
Ela se juntou ao grupo de manifestantes ambientais.