The Sgian Dubh

The Sgian Dubh (pronounced skee-an-doo) is a small, single-edged knife worn as part of traditional Scottish Highand dress. It is worn tucked into the top of the kilt sock with only the upper portion of the hilt visible. The Sgian Dubh is normally worn on the same side as the dominant hand.

The name comes from the Scottish Gaelic Sgian Dubh.  Sgian meaning 'knife' and Dubh meaning 'black', with the secondary meaning of 'hidden'.

Origins

The Sgian Dubh may have evolved from the sgian achlais, a dagger that could be concealed under the armpit. Used by the Scots of the 16th, 17th and 18th centuries, this knife was slightly larger than the average modern sgian-dubh and was carried in the upper sleeve or lining of the body of the jacket.

Draconian Scots laws, introduced by the Scots Privy Council under the Stewart King in the late 1500's, outlawed hidden weapons with the intention of reducing interclan feuds and duelling.  Following the introduction of these laws the carrying of hidden weapons (the Sgian) may have begun to transition from armpit pocket to the top of the sock on the leg. 

Additionally, codes of Highland courtesy and etiquette would demand that when entering the home of a friend, any concealed weapons would be revealed. It follows that the sgian-achlais would be removed from its hiding place and displayed in the stocking top held securely by the garter.

The sgian-dubh, as we know it today, can be seen in portraits of kilted men of the mid-19th century. A portrait by Sir Henry Raeburn of Colonel Alasdair Ranaldson MacDonell of Glengarry hangs in the National Gallery of Scotland; it shows hanging from his belt on his right hand side a Highland Scottish dirk, and visible at the top of his right stocking what appears to be a nested set of two sgian dubhs.