cordon

noun1 a line or circle of police, soldiers, or guards preventing access to or from an area or building :troops threw a cordon around the headquarters.2 an ornamental cord or braid.3 Architecture another term for stringcourse .verb [ trans. ] ( cordon off)prevent access to or from (an area or building) by surrounding it with police or other guards : the city center was cordoned off after fires were discovered in two stores.