Jack

The use of this word to denote a type of flag is most familiar in relation to the UK's national flag (the Union Flag, or Union Jack). According to Wikipedia, it is said to originate from the signature ('Jacques') of King James I, in whose reign the Union Flag was designed.

Wikipedia also refers however to the website of the Flag Institute ("the UK's national flag charity"), which disagrees: "most of the evidence points to the name being derived from the use of the word 'jack' as a diminutive. This word was in use before 1600 to describe a small flag flown from the small mast mounted on the bowsprit [of a ship], and by 1627 it appears that a small version of the Union flag was commonly flown in this position."

Commander Bruce Nicolls OBE RN (Retd) of the Flag Institute goes on to say that "For some years it was called just 'the Jack', or 'Jack flag', or 'the King's Jack', but by 1674, while formally referred to as 'His Majesty's Jack', it was commonly called the Union Jack, and this was officially acknowledged.

"In the 18th century the small mast on the bowsprit was replaced by staysails on the stays between the bowsprit and the foremast. By this time the Ensign had become the principal naval distinguishing flag, so it became the practice to fly the Union Jack only in harbour, on a specially rigged staff in the bows of the ships, the jackstaff. It should thus be noted that the jack flag had existed for over a hundred and fifty years before the jack staff came into being, and its name was related to its size rather than to the position in which it was flown."

Cdr. Nicolls concludes by debunking the myth that the Union Flag should only be described as the Union Jack when flown in the bows of a warship: "this is a relatively recent idea. From early in its life the Admiralty itself frequently referred to the flag as the Union Jack, whatever its use, and in 1902 an Admiralty Circular announced that Their Lordships had decided that either name could be used officially. Such use was given Parliamentary approval in 1908 when it was stated that 'the Union Jack should be regarded as the National flag'."