1 [count] : an organization of workers formed to protect the rights and interests of its members
▪ She joined the teachers' union. ▪ union members/leaders/officials —called also (US) labor union (Brit) trade union 2 [noncount] : an act of joining two or more things together
▪ An embryo is created through the union of sperm and egg. ▪ a perfect union of Eastern and Western music 3 [singular] : a group of states or nations that are ruled by one government or that agree to work together
▪ the former Soviet Union ▪ the European Union 4 the Union a : the United States
▪ Utah joined the Union in 1896. ◊The State of the Union address is a yearly speech given by the U.S. President to Congress and the people to tell them about important things that are affecting the country.
b : the group of northern states that supported the federal government during the American Civil War
▪ One brother fought for the Union and one for the Confederacy. — often used as Union before another noun ▪ Union soldiers 5 [count] : an organized group of people, businesses, etc., that have the same purpose or interest
▪ the American Civil Liberties Union ▪ the International Skating Union — see also student union 6 formal : the act of getting married or of causing two people to be married [noncount] ▪ the union of two people in marriage [count] ▪ They celebrated their union [=marriage] with more than 200 friends and family members. — see also civil union 7 [count, noncount] formal : the activity or an act of having sex
▪ sexual union