As a Noun:
1. A public meeting or march which is held by people to show their opposition to something or their support for it. English = demonstration, protest.
2. A group of people, usually trade union members, who stand outside a place of work in order to protest about something, to prevent people from going in, or to persuade the workers to join a strike. English = picket.
3. A large notice that is carried in a march or demonstration or is displayed in a public place. English = placard.
As a Verb or Adjective:
1. To take part in a march or a meeting to show your opposition to something or your support for it. English = demonstrate, protest.
2. Of a group of people, usually trade union members, to stand outside a place of work in order to protest about something, to prevent people from going in, or to persuade the workers to join a strike. English = picket.
3. To hold a placard.