union(n) a labor group formed to protect the rights and interests of its members
union activist(n) a person who uses or supports strong actions,such as stikes,to represent workers interests and help improve pay or working conditions
strike(n) a period of time when workers stop work in order to force an employer to agree to their demands
call a strike(expression) to give the order for a strike
labor movement(n) an organized effort by workers to improve their status by united action through labor unions