The term 'striker' can be defined as a PICKET, which is a person who stands outside of a place of business or other organization to protest or draw attention to a particular cause. Picketing is a form of civil disobedience that has been used for centuries to bring attention to social and political issues. The term 'striker' is often used to refer to someone who is actively involved in a labor strike, which is a collective action taken by workers to protest unfair working conditions or wages.