Act of Union in British history, either of the parliamentary acts by which the countries of the United Kingdom were brought together as a political whole. By the first Act of Union (1707) Scotland was joined with England to form Great Britain. The second Act of Union (1801) established the United Kingdom of Great Britain and Ireland. Wales had been incorporated with England in 1536.
Union flag the national flag of the United Kingdom, consisting of red and white crosses on a blue background and formed by combining the flags of St George, St Andrew, and St Patrick; the name Union Jack is now frequently used.
union is strength proverbial saying, mid 17th century; early classical versions include Homer's Iliad ‘even weak men have strength in unity’ and the Latin tag ‘force united is stronger’. (Unity is a popular alternative for union in this saying, especially when used as a trade-union slogan.)
Union Jack originally and properly a small Union flag flown as the jack of a ship (a small version of a national flag flown at the bow of a vessel in harbour to indicate its nationality); more generally, the Union flag in any size or adaptation, regarded as the national ensign.
See also State of the Union message.