What is a name for a small dagger?

A small dagger worn in the sock by Scotsmen is called a "Sgian Dhubh" which is pronounced as if it were spelled SKI-UN-DOO. Nowadays it is mostly decorative but in days now long past is was a backup concealed weapon that was carried for when a man would normally park his main weapons (as when entering a friends home) just in case his "friend" was no longer trustworthy. politics being what they are.