A cun, often glossed as the Chinese inch, is a traditional Chinese unit of length. Its traditional measure is the width of a person's thumb at the knuckle, whereas the width of the two forefingers denotes 1.5 cun and the width of four fingers side-by-side is 3 cuns. It continues to be used to chart acupuncture points on the human body, and, in various uses for traditional Chinese medicine.