union

Everyday

1. A union is a group of workers who join together to protect their pay and rights (a trade union, a labor union). tree →
2. A union is a group of countries or states joined together, such as the European Union or the United States (once called «the Union»). tree →
3. Union is the act of joining things together. tree →
4. In maths, the union of two sets is all the things that are in one set or the other or both. tree →
5. A union can also mean a marriage between two people. tree →

In the lessons

In maths, sets: A ∪ B is the union — every member of both sets, each listed once. In history and social studies, unions of workers, and countries forming unions. A student union is a club for university students. The Union Jack is the flag of the United Kingdom. Phrases: «trade union», «the European Union», «Union Jack», «the union of two sets».

Examples

• The workers joined a union to ask for fair pay. tree →
• The United Kingdom is a union of four countries. tree →
• The union of the sets {1, 2, 3} and {3, 4} is {1, 2, 3, 4}. tree →
• The Union Jack flew over the town hall. tree →
• The union of two rivers made a big river. tree →
• Every member of the union voted. tree →
• For some years they lived happily together, and their union was blessed by the birth of two sons. tree →

Note

Countable noun: «a union», «unions». Starts with a «you» sound, so we say «a union», not «an union». In maths, the union counts shared members only once: the union of {1, 2} and {2, 3} has 3 members, not 4. Do not confuse with «onion».

In Jewish tradition

In maths, sets: A ∪ B is the union — every member of both sets, each listed once. In history and social studies, unions of workers, and countries forming unions. A student union is a club for university students. The Union Jack is the flag of the United Kingdom. Phrases: «trade union», «the European Union», «Union Jack», «the union of two sets».

Note

Countable noun: «a union», «unions». Starts with a «you» sound, so we say «a union», not «an union». In maths, the union counts shared members only once: the union of {1, 2} and {2, 3} has 3 members, not 4. Do not confuse with «onion».