Invention is a creation skill, where you use almost every other skill and a great number of items to train. You can do many activities using this skill, such as augmenting items for perks, and making new devices.
Tar Heel is the nickname for a native or resident of North Carolina as well as for the state itself, which is known as the Tar Heel State.
Tar-water is a Medieval medicine consisting of pine tar and water. It was foul tasting and so slowly dropped in popularity, but was revived in the Victorian era. The use of the medicine is mentioned in Great Expectations, Chapter 2 by Charles Dickens.