Definition of union

• n. - The act of uniting or joining two or more things into one, or the state of being united or joined; junction; coalition; combination.
• n. - Agreement and conjunction of mind, spirit, will, affections, or the like; harmony; concord.
• n. - That which is united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league; as, the weavers have formed a union; trades unions have become very numerous; the United States of America are often called the Union.
• n. - A textile fabric composed of two or more materials, as cotton, silk, wool, etc., woven together.
• n. - A large, fine pearl.
• n. - A device emblematic of union, used on a national flag or ensign, sometimes, as in the military standard of Great Britain, covering the whole field; sometimes, as in the flag of the United States, and the English naval and marine flag, occupying the upper inner corner, the rest of the flag being called the fly. Also, a flag having such a device; especially, the flag of Great Britain.
• n. - A joint or other connection uniting parts of machinery, or the like, as the elastic pipe of a tender connecting it with the feed pipe of a locomotive engine; especially, a pipe fitting for connecting pipes, or pipes and fittings, in such a way as to facilitate disconnection.
• n. - A cask suspended on trunnions, in which fermentation is carried on.