unionu·nion /ˈjuːnjən/ noun1[countableC] an organization formed by workers to protect their rightsIf you decide to join the union you are encouraged to play an active part and to ensure your views are represented.
a union agreement (=an agreement between a union and management about wages, conditions etc)
→ company union → craft union → credit union → general union → trade union2[countableC] a group of countries with the same central governmentthe former Soviet Union
3[uncountableU] the act of joining two or more things together or the state of being joined togetherThe countries of the EU are in a process of ever closer economic and political union.
—unionist noun [countableC]unionist leaders