Dirk

A dirk is a long thrusting dagger. Historically, it was a personal weapon of officers engaged in naval hand-to-hand combat during the Age of Sail, as well as the personal sidearm of the officers of Scottish Highland regiments, and Japanese naval officers.

The term is associated with Scotland in the Early Modern Era, being attested from about 1600. The term was spelled dork or dirk during the 17th century, presumably from the Dutch, Swedish and Danish dolk, and German dolch, tolch from a West Slavic Tillich. The exact etymology is unclear. The modern spelling dirk is probably due to Samuel Johnson's 1755 Dictionary. The term is also used for "dagger" generically, especially in the context of prehistoric daggers such as the Oxborough dirk.

A thrusting weapon, the naval dirk was originally used as a boarding weapon and functional fighting dagger. It was worn by midshipmen and officers during the days of sail, gradually evolving into a ceremonial weapon and badge of office. In the Royal Navy, the naval dirk is still presented to junior officers; their basic design has changed little in the last 500 years.

The naval dirk (Polish kordzik, Russian кортик) became part of the uniform of naval officers and civilian officials in the Navy Department of the Russian Empire, and in the Soviet navy an element of the dress uniform of officers. Later, it became an element of other uniforms as well, e.g. of officers in the Russian and Polish army and air force, and of the police forces in some countries..

The Scottish dirk (also "Highland dirk", Scottish Gaelic: Biodag) is the traditional and ceremonial sidearm of the officers of Scottish Highland regiments. The development of the Scottish dirk as a weapon is unrelated to that of the naval dirk; it is a modern continuation of the 16th-century ballock or rondel dagger.

The traditional Scottish dirk is a development of the second half of the 18th century, when it became a popular item of military equipment in the Jacobite Risings. The 78th Fraser Highlanders, raised in 1757, wore full highland dress uniform; their equipment was described by Major-General James Stewart in 1780 as including a "musket and broadsword, to which many soldiers added the dirk at their own expense."

...
Wikipedia